Genetic Diseases, X-Linked: Genetic diseases that are linked to gene mutations on the X CHROMOSOME in humans (X CHROMOSOME, HUMAN) or the X CHROMOSOME in other species. Included here are animal models of human X-linked diseases.Genes, X-Linked: Genes that are located on the X CHROMOSOME.X Chromosome: The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species.Mental Retardation, X-Linked: A class of genetic disorders resulting in INTELLECTUAL DISABILITY that is associated either with mutations of GENES located on the X CHROMOSOME or aberrations in the structure of the X chromosome (SEX CHROMOSOME ABERRATIONS).X-Linked Inhibitor of Apoptosis Protein: An inhibitor of apoptosis protein that is translated by a rare cap-independent mechanism. It blocks caspase-mediated cellular destruction by inhibiting CASPASE 3; CASPASE 7; and CASPASE 9.Chromosomes, Human, X: The human female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in humans.Genetic Linkage: The co-inheritance of two or more non-allelic GENES due to their being located more or less closely on the same CHROMOSOME.Ichthyosis, X-Linked: Chronic form of ichthyosis that is inherited as a sex-linked recessive trait carried on the X-chromosome and transmitted to the male offspring. It is characterized by severe scaling, especially on the extremities, and is associated with steroid sulfatase deficiency.Dosage Compensation, Genetic: Genetic mechanisms that allow GENES to be expressed at a similar level irrespective of their GENE DOSAGE. This term is usually used in discussing genes that lie on the SEX CHROMOSOMES. Because the sex chromosomes are only partially homologous, there is a different copy number, i.e., dosage, of these genes in males vs. females. In DROSOPHILA, dosage compensation is accomplished by hypertranscription of genes located on the X CHROMOSOME. In mammals, dosage compensation of X chromosome genes is accomplished by random X CHROMOSOME INACTIVATION of one of the two X chromosomes in the female.X-Linked Combined Immunodeficiency Diseases: Forms of combined immunodeficiency caused by mutations in the gene for INTERLEUKIN RECEPTOR COMMON GAMMA SUBUNIT. Both severe and non-severe subtypes of the disease have been identified.Agammaglobulinemia: An immunologic deficiency state characterized by an extremely low level of generally all classes of gamma-globulin in the blood.Retinoschisis: A vitreoretinal dystrophy characterized by splitting of the neuroretinal layers. It occurs in two forms: degenerative retinoschisis and X chromosome-linked juvenile retinoschisis.Adrenoleukodystrophy: An X-linked recessive disorder characterized by the accumulation of saturated very long chain fatty acids in the LYSOSOMES of ADRENAL CORTEX and the white matter of CENTRAL NERVOUS SYSTEM. This disease occurs almost exclusively in the males. Clinical features include the childhood onset of ATAXIA; NEUROBEHAVIORAL MANIFESTATIONS; HYPERPIGMENTATION; ADRENAL INSUFFICIENCY; SEIZURES; MUSCLE SPASTICITY; and DEMENTIA. The slowly progressive adult form is called adrenomyeloneuropathy. The defective gene ABCD1 is located at Xq28, and encodes the adrenoleukodystrophy protein (ATP-BINDING CASSETTE TRANSPORTERS).X Chromosome Inactivation: A dosage compensation process occurring at an early embryonic stage in mammalian development whereby, at random, one X CHROMOSOME of the pair is repressed in the somatic cells of females.Pedigree: The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.Sex Chromosome Aberrations: Abnormal number or structure of the SEX CHROMOSOMES. Some sex chromosome aberrations are associated with SEX CHROMOSOME DISORDERS and SEX CHROMOSOME DISORDERS OF SEX DEVELOPMENT.Granulomatous Disease, Chronic: A defect of leukocyte function in which phagocytic cells ingest but fail to digest bacteria, resulting in recurring bacterial infections with granuloma formation. When chronic granulomatous disease is caused by mutations in the CYBB gene, the condition is inherited in an X-linked recessive pattern. When chronic granulomatous disease is caused by CYBA, NCF1, NCF2, or NCF4 gene mutations, the condition is inherited in an autosomal recessive pattern.Sex Chromosomes: The homologous chromosomes that are dissimilar in the heterogametic sex. There are the X CHROMOSOME, the Y CHROMOSOME, and the W, Z chromosomes (in animals in which the female is the heterogametic sex (the silkworm moth Bombyx mori, for example)). In such cases the W chromosome is the female-determining and the male is ZZ. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Hypophosphatemia, Familial: An inherited condition of abnormally low serum levels of PHOSPHATES (below 1 mg/liter) which can occur in a number of genetic diseases with defective reabsorption of inorganic phosphorus by the PROXIMAL RENAL TUBULES. This leads to phosphaturia, HYPOPHOSPHATEMIA, and disturbances of cellular and organ functions such as those in X-LINKED HYPOPHOSPHATEMIC RICKETS; OSTEOMALACIA; and FANCONI SYNDROME.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Nephritis, Hereditary: A group of inherited conditions characterized initially by HEMATURIA and slowly progressing to RENAL INSUFFICIENCY. The most common form is the Alport syndrome (hereditary nephritis with HEARING LOSS) which is caused by mutations in genes for TYPE IV COLLAGEN and defective GLOMERULAR BASEMENT MEMBRANE.Steryl-Sulfatase: An arylsulfatase with high specificity towards sulfated steroids. Defects in this enzyme are the cause of ICHTHYOSIS, X-LINKED.Nystagmus, Congenital: Nystagmus present at birth or caused by lesions sustained in utero or at the time of birth. It is usually pendular, and is associated with ALBINISM and conditions characterized by early loss of central vision. Inheritance patterns may be X-linked, autosomal dominant, or recessive. (Adams et al., Principles of Neurology, 6th ed, p275)Retinitis Pigmentosa: Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.Intellectual Disability: Subnormal intellectual functioning which originates during the developmental period. This has multiple potential etiologies, including genetic defects and perinatal insults. Intelligence quotient (IQ) scores are commonly used to determine whether an individual has an intellectual disability. IQ scores between 70 and 79 are in the borderline range. Scores below 67 are in the disabled range. (from Joynt, Clinical Neurology, 1992, Ch55, p28)Syndrome: A characteristic symptom complex.Heterozygote: An individual having different alleles at one or more loci regarding a specific character.Ectodermal Dysplasia: A group of hereditary disorders involving tissues and structures derived from the embryonic ectoderm. They are characterized by the presence of abnormalities at birth and involvement of both the epidermis and skin appendages. They are generally nonprogressive and diffuse. Various forms exist, including anhidrotic and hidrotic dysplasias, FOCAL DERMAL HYPOPLASIA, and aplasia cutis congenita.Immunologic Deficiency Syndromes: Syndromes in which there is a deficiency or defect in the mechanisms of immunity, either cellular or humoral.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Familial Hypophosphatemic Rickets: A hereditary disorder characterized by HYPOPHOSPHATEMIA; RICKETS; OSTEOMALACIA; renal defects in phosphate reabsorption and vitamin D metabolism; and growth retardation. Autosomal and X-linked dominant and recessive variants have been reported.Ichthyosis: Any of several generalized skin disorders characterized by dryness, roughness, and scaliness, due to hypertrophy of the stratum corneum epidermis. Most are genetic, but some are acquired, developing in association with other systemic disease or genetic syndrome.Fabry Disease: An X-linked inherited metabolic disease caused by a deficiency of lysosomal ALPHA-GALACTOSIDASE A. It is characterized by intralysosomal accumulation of globotriaosylceramide and other GLYCOSPHINGOLIPIDS in blood vessels throughout the body leading to multi-system complications including renal, cardiac, cerebrovascular, and skin disorders.Rett Syndrome: An inherited neurological developmental disorder that is associated with X-LINKED INHERITANCE and may be lethal in utero to hemizygous males. The affected female is normal until the age of 6-25 months when progressive loss of voluntary control of hand movements and communication skills; ATAXIA; SEIZURES; autistic behavior; intermittent HYPERVENTILATION; and HYPERAMMONEMIA appear. (From Menkes, Textbook of Child Neurology, 5th ed, p199)Heterozygote Detection: Identification of genetic carriers for a given trait.Wiskott-Aldrich Syndrome: A rare, X-linked immunodeficiency syndrome characterized by ECZEMA; LYMPHOPENIA; and, recurrent pyogenic infection. It is seen exclusively in young boys. Typically, IMMUNOGLOBULIN M levels are low and IMMUNOGLOBULIN A and IMMUNOGLOBULIN E levels are elevated. Lymphoreticular malignancies are common.DNA Mutational Analysis: Biochemical identification of mutational changes in a nucleotide sequence.Chromosome Mapping: Any method used for determining the location of and relative distances between genes on a chromosome.Anemia, Sideroblastic: Anemia characterized by the presence of erythroblasts containing excessive deposits of iron in the marrow.Ectodermal Dysplasia 1, Anhidrotic: An X-linked form of ectodermal dysplasia which results from mutations of the gene encoding ECTODYSPLASIN.Genes, Recessive: Genes that influence the PHENOTYPE only in the homozygous state.Eye ProteinsIncontinentia Pigmenti: A genodermatosis occurring mostly in females and characterized by skin changes in three phases - vesiculobullous, verrucous papillomatous, and macular melanodermic. Hyperpigmentation is bizarre and irregular. Sixty percent of patients have abnormalities of eyes, teeth, central nervous system, and skin appendages.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Hypergammaglobulinemia: An excess of GAMMA-GLOBULINS in the serum due to chronic infections or PARAPROTEINEMIAS.Severe Combined Immunodeficiency: Group of rare congenital disorders characterized by impairment of both humoral and cell-mediated immunity, leukopenia, and low or absent antibody levels. It is inherited as an X-linked or autosomal recessive defect. Mutations occurring in many different genes cause human Severe Combined Immunodeficiency (SCID).Lymphoproliferative Disorders: Disorders characterized by proliferation of lymphoid tissue, general or unspecified.alpha-Galactosidase: An enzyme that catalyzes the hydrolysis of terminal, non-reducing alpha-D-galactose residues in alpha-galactosides including galactose oligosaccharides, galactomannans, and galactolipids.Exons: The parts of a transcript of a split GENE remaining after the INTRONS are removed. They are spliced together to become a MESSENGER RNA or other functional RNA.Hyper-IgM Immunodeficiency Syndrome, Type 1: An X-linked hyper-IgM immunodeficiency subtype resulting from mutation in the gene encoding CD40 LIGAND.Kallmann Syndrome: A genetically heterogeneous disorder caused by hypothalamic GNRH deficiency and OLFACTORY NERVE defects. It is characterized by congenital HYPOGONADOTROPIC HYPOGONADISM and ANOSMIA, possibly with additional midline defects. It can be transmitted as an X-linked (GENETIC DISEASES, X-LINKED), an autosomal dominant, or an autosomal recessive trait.Y Chromosome: The male sex chromosome, being the differential sex chromosome carried by half the male gametes and none of the female gametes in humans and in some other male-heterogametic species in which the homologue of the X chromosome has been retained.Methyl-CpG-Binding Protein 2: A DNA-binding protein that interacts with methylated CPG ISLANDS. It plays a role in repressing GENETIC TRANSCRIPTION and is frequently mutated in RETT SYNDROME.Phosphoglycerate Kinase: An enzyme catalyzing the transfer of a phosphate group from 3-phospho-D-glycerate in the presence of ATP to yield 3-phospho-D-glyceroyl phosphate and ADP. EC Punctata: A heterogeneous group of bone dysplasias, the common character of which is stippling of the epiphyses in infancy. The group includes a severe autosomal recessive form (CHONDRODYSPLASIA PUNCTATA, RHIZOMELIC), an autosomal dominant form (Conradi-Hunermann syndrome), and a milder X-linked form. Metabolic defects associated with impaired peroxisomes are present only in the rhizomelic form.Mutation, Missense: A mutation in which a codon is mutated to one directing the incorporation of a different amino acid. This substitution may result in an inactive or unstable product. (From A Dictionary of Genetics, King & Stansfield, 5th ed)Muscular Dystrophy, Emery-Dreifuss: A heterogenous group of inherited muscular dystrophy without the involvement of nervous system. The disease is characterized by MUSCULAR ATROPHY; MUSCLE WEAKNESS; CONTRACTURE of the elbows; ACHILLES TENDON; and posterior cervical muscles; with or without cardiac features. There are several INHERITANCE PATTERNS including X-linked (X CHROMOSOME), autosomal dominant, and autosomal recessive gene mutations.Myopathies, Structural, Congenital: A heterogeneous group of diseases characterized by the early onset of hypotonia, developmental delay of motor skills, non-progressive weakness. Each of these disorders is associated with a specific histologic muscle fiber abnormality.Arylsulfatases: Enzymes that catalyze the hydrolysis of a phenol sulfate to yield a phenol and sulfate. Arylsulfatase A, B, and C have been separated. A deficiency of arylsulfatases is one of the causes of metachromatic leukodystrophy (LEUKODYSTROPHY, METACHROMATIC). EC Phosphoribosyltransferase: An enzyme that catalyzes the conversion of 5-phosphoribosyl-1-pyrophosphate and hypoxanthine, guanine, or 6-mercaptopurine to the corresponding 5'-mononucleotides and pyrophosphate. The enzyme is important in purine biosynthesis as well as central nervous system functions. Complete lack of enzyme activity is associated with the LESCH-NYHAN SYNDROME, while partial deficiency results in overproduction of uric acid. EC, Ocular: Albinism affecting the eye in which pigment of the hair and skin is normal or only slightly diluted. The classic type is X-linked (Nettleship-Falls), but an autosomal recessive form also exists. Ocular abnormalities may include reduced pigmentation of the iris, nystagmus, photophobia, strabismus, and decreased visual acuity.Color Vision Defects: Defects of color vision are mainly hereditary traits but can be secondary to acquired or developmental abnormalities in the CONES (RETINA). Severity of hereditary defects of color vision depends on the degree of mutation of the ROD OPSINS genes (on X CHROMOSOME and CHROMOSOME 3) that code the photopigments for red, green and blue.Wiskott-Aldrich Syndrome Protein: WASP protein is mutated in WISKOTT-ALDRICH SYNDROME and is expressed primarily in hematopoietic cells. It is the founding member of the WASP protein family and interacts with CDC42 PROTEIN to help regulate ACTIN polymerization.Mosaicism: The occurrence in an individual of two or more cell populations of different chromosomal constitutions, derived from a single ZYGOTE, as opposed to CHIMERISM in which the different cell populations are derived from more than one zygote.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Electroretinography: Recording of electric potentials in the retina after stimulation by light.Choroideremia: An X chromosome-linked abnormality characterized by atrophy of the choroid and degeneration of the retinal pigment epithelium causing night blindness.Codon, Nonsense: An amino acid-specifying codon that has been converted to a stop codon (CODON, TERMINATOR) by mutation. Its occurance is abnormal causing premature termination of protein translation and results in production of truncated and non-functional proteins. A nonsense mutation is one that converts an amino acid-specific codon to a stop codon.Thymopoietins: Two closely related polypeptides (molecular weight 7,000) isolated from the thymus gland. These hormones induce the differentiation of prothymocytes to thymocytes within the thymus. They also cause a delayed impairment of neuromuscular transmission in vivo and are therefore believed to be the agent responsible for myasthenia gravis.Glucosephosphate DehydrogenasePoint Mutation: A mutation caused by the substitution of one nucleotide for another. This results in the DNA molecule having a change in a single base pair.Dystrophin: A muscle protein localized in surface membranes which is the product of the Duchenne/Becker muscular dystrophy gene. Individuals with Duchenne muscular dystrophy usually lack dystrophin completely while those with Becker muscular dystrophy have dystrophin of an altered size. It shares features with other cytoskeletal proteins such as SPECTRIN and alpha-actinin but the precise function of dystrophin is not clear. One possible role might be to preserve the integrity and alignment of the plasma membrane to the myofibrils during muscle contraction and relaxation. MW 400 kDa.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Diffuse Cerebral Sclerosis of Schilder: A rare central nervous system demyelinating condition affecting children and young adults. Pathologic findings include a large, sharply defined, asymmetric focus of myelin destruction that may involve an entire lobe or cerebral hemisphere. The clinical course tends to be progressive and includes dementia, cortical blindness, cortical deafness, spastic hemiplegia, and pseudobulbar palsy. Concentric sclerosis of Balo is differentiated from diffuse cerebral sclerosis of Schilder by the pathologic finding of alternating bands of destruction and preservation of myelin in concentric rings. Alpers' Syndrome refers to a heterogeneous group of diseases that feature progressive cerebral deterioration and liver disease. (From Adams et al., Principles of Neurology, 6th ed, p914; Dev Neurosci 1991;13(4-5):267-73)Abnormalities, MultipleGenetic Markers: A phenotypically recognizable genetic trait which can be used to identify a genetic locus, a linkage group, or a recombination event.5-Aminolevulinate Synthetase: An enzyme of the transferase class that catalyzes condensation of the succinyl group from succinyl coenzyme A with glycine to form delta-aminolevulinate. It is a pyridoxyal phosphate protein and the reaction occurs in mitochondria as the first step of the heme biosynthetic pathway. The enzyme is a key regulatory enzyme in heme biosynthesis. In liver feedback is inhibited by heme. EC Tyrosine Phosphatases, Non-Receptor: A subcategory of protein tyrosine phosphatases that occur in the CYTOPLASM. Many of the proteins in this category play a role in intracellular signal transduction.Night Blindness: Failure or imperfection of vision at night or in dim light, with good vision only on bright days. (Dorland, 27th ed)Mucopolysaccharidosis II: Systemic lysosomal storage disease marked by progressive physical deterioration and caused by a deficiency of L-sulfoiduronate sulfatase. This disease differs from MUCOPOLYSACCHARIDOSIS I by slower progression, lack of corneal clouding, and X-linked rather than autosomal recessive inheritance. The mild form produces near-normal intelligence and life span. The severe form usually causes death by age 15.Oculocerebrorenal Syndrome: A sex-linked recessive disorder affecting multiple systems including the EYE, the NERVOUS SYSTEM, and the KIDNEY. Clinical features include congenital CATARACT; MENTAL RETARDATION; and renal tubular dysfunction (FANCONI SYNDROME; RENAL TUBULAR ACIDOSIS; X-LINKED HYPOPHOSPHATEMIA or vitamin-D-resistant rickets) and SCOLIOSIS. This condition is due to a deficiency of phosphatidylinositol 4,5-bisphosphate-5-phosphatase leading to defects in PHOSPHATIDYLINOSITOL metabolism and INOSITOL signaling pathway. (from Menkes, Textbook of Child Neurology, 5th ed, p60; Am J Hum Genet 1997 Jun;60(6):1384-8)Genes, Y-Linked: Genes that are located on the Y CHROMOSOME.Intracellular Signaling Peptides and Proteins: Proteins and peptides that are involved in SIGNAL TRANSDUCTION within the cell. Included here are peptides and proteins that regulate the activity of TRANSCRIPTION FACTORS and cellular processes in response to signals from CELL SURFACE RECEPTORS. Intracellular signaling peptide and proteins may be part of an enzymatic signaling cascade or act through binding to and modifying the action of other signaling factors.Frameshift Mutation: A type of mutation in which a number of NUCLEOTIDES deleted from or inserted into a protein coding sequence is not divisible by three, thereby causing an alteration in the READING FRAMES of the entire coding sequence downstream of the mutation. These mutations may be induced by certain types of MUTAGENS or may occur spontaneously.Hemizygote: An individual having only one allele at a given locus because of the loss of the other allele through a mutation (e.g., CHROMOSOME DELETION).Menkes Kinky Hair Syndrome: An inherited disorder of copper metabolism transmitted as an X-linked trait and characterized by the infantile onset of HYPOTHERMIA, feeding difficulties, hypotonia, SEIZURES, bony deformities, pili torti (twisted hair), and severely impaired intellectual development. Defective copper transport across plasma and endoplasmic reticulum membranes results in copper being unavailable for the synthesis of several copper containing enzymes, including PROTEIN-LYSINE 6-OXIDASE; CERULOPLASMIN; and SUPEROXIDE DISMUTASE. Pathologic changes include defects in arterial elastin, neuronal loss, and gliosis. (From Menkes, Textbook of Child Neurology, 5th ed, p125)B-Lymphocytes: Lymphoid cells concerned with humoral immunity. They are short-lived cells resembling bursa-derived lymphocytes of birds in their production of immunoglobulin upon appropriate stimulation.Lod Score: The total relative probability, expressed on a logarithmic scale, that a linkage relationship exists among selected loci. Lod is an acronym for "logarithmic odds."Muscular Dystrophy, Duchenne: An X-linked recessive muscle disease caused by an inability to synthesize DYSTROPHIN, which is involved with maintaining the integrity of the sarcolemma. Muscle fibers undergo a process that features degeneration and regeneration. Clinical manifestations include proximal weakness in the first few years of life, pseudohypertrophy, cardiomyopathy (see MYOCARDIAL DISEASES), and an increased incidence of impaired mentation. Becker muscular dystrophy is a closely related condition featuring a later onset of disease (usually adolescence) and a slowly progressive course. (Adams et al., Principles of Neurology, 6th ed, p1415)Dyskeratosis Congenita: A predominantly X-linked recessive syndrome characterized by a triad of reticular skin pigmentation, nail dystrophy and leukoplakia of mucous membranes. Oral and dental abnormalities may also be present. Complications are a predisposition to malignancy and bone marrow involvement with pancytopenia. (from Int J Paediatr Dent 2000 Dec;10(4):328-34) The X-linked form is also known as Zinsser-Cole-Engman syndrome and involves the gene which encodes a highly conserved protein called dyskerin.Hypohidrosis: Abnormally diminished or absent perspiration. Both generalized and segmented (reduced or absent sweating in circumscribed locations) forms of the disease are usually associated with other underlying conditions.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Xedar Receptor: An ectodysplasin receptor subtype that is specific for ECTODYSPLASIN A2. Unlike the EDAR RECEPTOR the Xedar receptor signals through direct association with TNF RECEPTOR-ASSOCIATED FACTORS. The protein name derives from the fact that gene that encodes it resides on the X CHROMOSOME.Sex Determination Analysis: Validation of the SEX of an individual by inspection of the GONADS and/or by genetic tests.Genes, Lethal: Genes whose loss of function or gain of function MUTATION leads to the death of the carrier prior to maturity. They may be essential genes (GENES, ESSENTIAL) required for viability, or genes which cause a block of function of an essential gene at a time when the essential gene function is required for viability.Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.Genes, Dominant: Genes that influence the PHENOTYPE both in the homozygous and the heterozygous state.SulfatasesBarth Syndrome: Rare congenital X-linked disorder of lipid metabolism. Barth syndrome is transmitted in an X-linked recessive pattern. The syndrome is characterized by muscular weakness, growth retardation, DILATED CARDIOMYOPATHY, variable NEUTROPENIA, 3-methylglutaconic aciduria (type II) and decreases in mitochondrial CARDIOLIPIN level. Other biochemical and morphological mitochondrial abnormalities also exist.Polymorphism, Single-Stranded Conformational: Variation in a population's DNA sequence that is detected by determining alterations in the conformation of denatured DNA fragments. Denatured DNA fragments are allowed to renature under conditions that prevent the formation of double-stranded DNA and allow secondary structure to form in single stranded fragments. These fragments are then run through polyacrylamide gels to detect variations in the secondary structure that is manifested as an alteration in migration through the gels.DAX-1 Orphan Nuclear Receptor: An orphan nuclear receptor that is implicated in regulation of steroidogenic pathways. It is unlike most orphan nuclear receptors in that it appears to lack an essential DNA-binding domain and instead acts as a transcriptional co-repressor. Mutations in the gene Dax-1 cause congenital adrenal hypoplasia.Muscular Dystrophies: A heterogeneous group of inherited MYOPATHIES, characterized by wasting and weakness of the SKELETAL MUSCLE. They are categorized by the sites of MUSCLE WEAKNESS; AGE OF ONSET; and INHERITANCE PATTERNS.Nuclear Proteins: Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.Hybrid Cells: Any cell, other than a ZYGOTE, that contains elements (such as NUCLEI and CYTOPLASM) from two or more different cells, usually produced by artificial CELL FUSION.Drosophila melanogaster: A species of fruit fly much used in genetics because of the large size of its chromosomes.RNA, Long Noncoding: A class of untranslated RNA molecules that are typically greater than 200 nucleotides in length and do not code for proteins. Members of this class have been found to play roles in transcriptional regulation, post-transcriptional processing, CHROMATIN REMODELING, and in the epigenetic control of chromatin.Mice, Mutant Strains: Mice bearing mutant genes which are phenotypically expressed in the animals.Crosses, Genetic: Deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent. The parent organisms must be genetically compatible and may be from different varieties or closely related species.Models, Genetic: Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Diabetes Insipidus, Nephrogenic: A genetic or acquired polyuric disorder characterized by persistent hypotonic urine and HYPOKALEMIA. This condition is due to renal tubular insensitivity to VASOPRESSIN and failure to reduce urine volume. It may be the result of mutations of genes encoding VASOPRESSIN RECEPTORS or AQUAPORIN-2; KIDNEY DISEASES; adverse drug effects; or complications from PREGNANCY.DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).Apoptosis: One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.Sequence Deletion: Deletion of sequences of nucleic acids from the genetic material of an individual.Membrane Glycoproteins: Glycoproteins found on the membrane or surface of cells.Erucic Acids: cis-13-Docosenoic Acids. 22-Carbon monounsaturated, monocarboxylic acids.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Gene Deletion: A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.Drosophila: A genus of small, two-winged flies containing approximately 900 described species. These organisms are the most extensively studied of all genera from the standpoint of genetics and cytology.Cell Line: Established cell cultures that have the potential to propagate indefinitely.NADPH Oxidase: A flavoprotein enzyme that catalyzes the univalent reduction of OXYGEN using NADPH as an electron donor to create SUPEROXIDE ANION. The enzyme is dependent on a variety of CYTOCHROMES. Defects in the production of superoxide ions by enzymes such as NADPH oxidase result in GRANULOMATOUS DISEASE, CHRONIC.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Androgen-Insensitivity Syndrome: A disorder of sexual development transmitted as an X-linked recessive trait. These patients have a karyotype of 46,XY with end-organ resistance to androgen due to mutations in the androgen receptor (RECEPTORS, ANDROGEN) gene. Severity of the defect in receptor quantity or quality correlates with their phenotypes. In these genetic males, the phenotypic spectrum ranges from those with normal female external genitalia, through those with genital ambiguity as in Reifenstein Syndrome, to that of a normal male with INFERTILITY.Genetic Variation: Genotypic differences observed among individuals in a population.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Interleukin Receptor Common gamma Subunit: An interleukin receptor subunit that was originally discovered as a component of the INTERLEUKIN 2 RECEPTOR. It was subsequently found to be a component of several other receptors including the INTERLEUKIN 4 RECEPTOR, the INTERLEUKIN 7 RECEPTOR, the INTERLEUKIN-9 RECEPTOR, the INTERLEUKIN-15 RECEPTOR, and the INTERLEUKIN-21 RECEPTOR. Mutations in the gene for the interleukin receptor common gamma chain have been associated with X-LINKED COMBINED IMMUNODEFICIENCY DISEASES.Cytochrome b Group: Cytochromes (electron-transporting proteins) with protoheme (HEME B) as the prosthetic group.Spasms, Infantile: An epileptic syndrome characterized by the triad of infantile spasms, hypsarrhythmia, and arrest of psychomotor development at seizure onset. The majority present between 3-12 months of age, with spasms consisting of combinations of brief flexor or extensor movements of the head, trunk, and limbs. The condition is divided into two forms: cryptogenic (idiopathic) and symptomatic (secondary to a known disease process such as intrauterine infections; nervous system abnormalities; BRAIN DISEASES, METABOLIC, INBORN; prematurity; perinatal asphyxia; TUBEROUS SCLEROSIS; etc.). (From Menkes, Textbook of Child Neurology, 5th ed, pp744-8)Haplotypes: The genetic constitution of individuals with respect to one member of a pair of allelic genes, or sets of genes that are closely linked and tend to be inherited together such as those of the MAJOR HISTOCOMPATIBILITY COMPLEX.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.Focal Dermal Hypoplasia: A genetic skin disease characterized by hypoplasia of the dermis, herniations of fat, and hand anomalies. It is found exclusively in females and transmitted as an X-linked dominant trait.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Muscle Hypotonia: A diminution of the skeletal muscle tone marked by a diminished resistance to passive stretching.Glycogen Storage Disease Type IIb: An X-linked dominant multisystem disorder resulting in cardiomyopathy, myopathy and INTELLECTUAL DISABILITY. It is caused by mutation in the gene encoding LYSOSOMAL-ASSOCIATED MEMBRANE PROTEIN 2.Lesch-Nyhan Syndrome: An inherited disorder transmitted as a sex-linked trait and caused by a deficiency of an enzyme of purine metabolism; HYPOXANTHINE PHOSPHORIBOSYLTRANSFERASE. Affected individuals are normal in the first year of life and then develop psychomotor retardation, extrapyramidal movement disorders, progressive spasticity, and seizures. Self-destructive behaviors such as biting of fingers and lips are seen frequently. Intellectual impairment may also occur but is typically not severe. Elevation of uric acid in the serum leads to the development of renal calculi and gouty arthritis. (Menkes, Textbook of Child Neurology, 5th ed, pp127)Nitroblue Tetrazolium: Colorless to yellow dye that is reducible to blue or black formazan crystals by certain cells; formerly used to distinguish between nonbacterial and bacterial diseases, the latter causing neutrophils to reduce the dye; used to confirm diagnosis of chronic granulomatous disease.Collagen Type IV: A non-fibrillar collagen found in the structure of BASEMENT MEMBRANE. Collagen type IV molecules assemble to form a sheet-like network which is involved in maintaining the structural integrity of basement membranes. The predominant form of the protein is comprised of two alpha1(IV) subunits and one alpha2(IV) subunit, however, at least six different alpha subunits can be incorporated into the heterotrimer.Family Health: The health status of the family as a unit including the impact of the health of one member of the family on the family as a unit and on individual family members; also, the impact of family organization or disorganization on the health status of its members.Microphthalmos: Congenital or developmental anomaly in which the eyeballs are abnormally small.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.Photophobia: Abnormal sensitivity to light. This may occur as a manifestation of EYE DISEASES; MIGRAINE; SUBARACHNOID HEMORRHAGE; MENINGITIS; and other disorders. Photophobia may also occur in association with DEPRESSION and other MENTAL DISORDERS.Introns: Sequences of DNA in the genes that are located between the EXONS. They are transcribed along with the exons but are removed from the primary gene transcript by RNA SPLICING to leave mature RNA. Some introns code for separate genes.Transcription Factors: Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.Genetic Therapy: Techniques and strategies which include the use of coding sequences and other conventional or radical means to transform or modify cells for the purpose of treating or reversing disease conditions.Mice, Inbred C57BLEye Diseases, Hereditary: Transmission of gene defects or chromosomal aberrations/abnormalities which are expressed in extreme variation in the structure or function of the eye. These may be evident at birth, but may be manifested later with progression of the disorder.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.Gene Expression: The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.CD40 Ligand: A membrane glycoprotein and differentiation antigen expressed on the surface of T-cells that binds to CD40 ANTIGENS on B-LYMPHOCYTES and induces their proliferation. Mutation of the gene for CD40 ligand is a cause of HYPER-IGM IMMUNODEFICIENCY SYNDROME, TYPE 1.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Genes, Insect: The functional hereditary units of INSECTS.Ornithine Carbamoyltransferase Deficiency Disease: An inherited urea cycle disorder associated with deficiency of the enzyme ORNITHINE CARBAMOYLTRANSFERASE, transmitted as an X-linked trait and featuring elevations of amino acids and ammonia in the serum. Clinical features, which are more prominent in males, include seizures, behavioral alterations, episodic vomiting, lethargy, and coma. (Menkes, Textbook of Child Neurology, 5th ed, pp49-50)Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Lingual Frenum: MUCOUS MEMBRANE extending from floor of mouth to the under-surface of the tongue.Plasma Membrane Neurotransmitter Transport Proteins: A family of neurotransmitter transporter proteins that facilitate NEUROTRANSMITTER reuptake into PRESYNAPTIC TERMINALS. They may play a role in regulating the intensity and duration of neurotransmission.Pelizaeus-Merzbacher Disease: A rare, slowly progressive disorder of myelin formation. Subtypes are referred to as classic, congenital, transitional, and adult forms of this disease. The classic form is X-chromosome linked, has its onset in infancy and is associated with a mutation of the proteolipid protein gene. Clinical manifestations include TREMOR, spasmus nutans, roving eye movements, ATAXIA, spasticity, and NYSTAGMUS, CONGENITAL. Death occurs by the third decade of life. The congenital form has similar characteristics but presents early in infancy and features rapid disease progression. Transitional and adult subtypes have a later onset and less severe symptomatology. Pathologic features include patchy areas of demyelination with preservation of perivascular islands (trigoid appearance). (From Menkes, Textbook of Child Neurology, 5th ed, p190)Mice, Inbred CBACells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Polymorphism, Restriction Fragment Length: Variation occurring within a species in the presence or length of DNA fragment generated by a specific endonuclease at a specific site in the genome. Such variations are generated by mutations that create or abolish recognition sites for these enzymes or change the length of the fragment.Iduronate Sulfatase: An enzyme that specifically cleaves the ester sulfate of iduronic acid. Its deficiency has been demonstrated in Hunter's syndrome, which is characterized by an excess of dermatan sulfate and heparan sulfate. EC A disorder characterized by reduced synthesis of the alpha chains of hemoglobin. The severity of this condition can vary from mild anemia to death, depending on the number of genes deleted.Protein-Tyrosine Kinases: Protein kinases that catalyze the PHOSPHORYLATION of TYROSINE residues in proteins with ATP or other nucleotides as phosphate donors.Cone Opsins: Photosensitive proteins expressed in the CONE PHOTORECEPTOR CELLS. They are the protein components of cone photopigments. Cone opsins are classified by their peak absorption wavelengths.Coffin-Lowry Syndrome: A rare, X-linked INTELLECTUAL DISABILITY syndrome that results from mutations in the RIBOSOMAL PROTEIN S6 KINASE gene. Typical manifestations of the disease include an intelligence quotient of less than 50, facial anomalies, and other malformations.Silene: A plant genus of the family CARYOPHYLLACEAE. The common name of campion is also used with LYCHNIS. The common name of 'pink' can be confused with other plants.Muscular Dystrophy, AnimalEnzyme Replacement Therapy: Therapeutic replacement or supplementation of defective or missing enzymes to alleviate the effects of enzyme deficiency (e.g., GLUCOSYLCERAMIDASE replacement for GAUCHER DISEASE).Sex Characteristics: Those characteristics that distinguish one SEX from the other. The primary sex characteristics are the OVARIES and TESTES and their related hormones. Secondary sex characteristics are those which are masculine or feminine but not directly related to reproduction.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.Chromosomes, Insect: Structures within the CELL NUCLEUS of insect cells containing DNA.Photoreceptor Cells, Vertebrate: Specialized PHOTOTRANSDUCTION neurons in the vertebrates, such as the RETINAL ROD CELLS and the RETINAL CONE CELLS. Non-visual photoreceptor neurons have been reported in the deep brain, the PINEAL GLAND and organs of the circadian system.Reverse Transcriptase Polymerase Chain Reaction: A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.Amelogenesis Imperfecta: A clinically and genetically heterogeneous group of hereditary conditions characterized by malformed DENTAL ENAMEL, usually involving DENTAL ENAMEL HYPOPLASIA and/or TOOTH HYPOMINERALIZATION.Sex Ratio: The number of males per 100 females.Pyruvate Dehydrogenase (Lipoamide): The E1 component of the multienzyme PYRUVATE DEHYDROGENASE COMPLEX. It is composed of 2 alpha subunits (pyruvate dehydrogenase E1 alpha subunit) and 2 beta subunits (pyruvate dehydrogenase E1 beta subunit).RNA, Untranslated: RNA which does not code for protein but has some enzymatic, structural or regulatory function. Although ribosomal RNA (RNA, RIBOSOMAL) and transfer RNA (RNA, TRANSFER) are also untranslated RNAs they are not included in this scope.Hypertrichosis: Excessive hair growth at inappropriate locations, such as on the extremities, the head, and the back. It is caused by genetic or acquired factors, and is an androgen-independent process. This concept does not include HIRSUTISM which is an androgen-dependent excess hair growth in WOMEN and CHILDREN.Genes: A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.Hypertelorism: Abnormal increase in the interorbital distance due to overdevelopment of the lesser wings of the sphenoid.DNA, Complementary: Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.Ribose-Phosphate Pyrophosphokinase: An enzyme that catalyzes the formation of phosphoribosyl pyrophosphate from ATP and ribose-5-phosphate. EC of Apoptosis Proteins: A conserved class of proteins that control APOPTOSIS in both VERTEBRATES and INVERTEBRATES. IAP proteins interact with and inhibit CASPASES, and they function as ANTI-APOPTOTIC PROTEINS. The protein class is defined by an approximately 80-amino acid motif called the baculoviral inhibitor of apoptosis repeat.Disorders of Sex Development: In gonochoristic organisms, congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical. Effects from exposure to abnormal levels of GONADAL HORMONES in the maternal environment, or disruption of the function of those hormones by ENDOCRINE DISRUPTORS are included.Immunoglobulin M: A class of immunoglobulin bearing mu chains (IMMUNOGLOBULIN MU-CHAINS). IgM can fix COMPLEMENT. The name comes from its high molecular weight and originally being called a macroglobulin.Genomic Imprinting: The variable phenotypic expression of a GENE depending on whether it is of paternal or maternal origin, which is a function of the DNA METHYLATION pattern. Imprinted regions are observed to be more methylated and less transcriptionally active. (Segen, Dictionary of Modern Medicine, 1992)Rickets: Disorders caused by interruption of BONE MINERALIZATION manifesting as OSTEOMALACIA in adults and characteristic deformities in infancy and childhood due to disturbances in normal BONE FORMATION. The mineralization process may be interrupted by disruption of VITAMIN D; PHOSPHORUS; or CALCIUM homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances.Sequence Inversion: The deletion and reinsertion of a segment of a nucleic acid sequence in the same place, but flipped in an opposite orientation.Dystonia: An attitude or posture due to the co-contraction of agonists and antagonist muscles in one region of the body. It most often affects the large axial muscles of the trunk and limb girdles. Conditions which feature persistent or recurrent episodes of dystonia as a primary manifestation of disease are referred to as DYSTONIC DISORDERS. (Adams et al., Principles of Neurology, 6th ed, p77)Genetic Diseases, Inborn: Diseases that are caused by genetic mutations present during embryo or fetal development, although they may be observed later in life. The mutations may be inherited from a parent's genome or they may be acquired in utero.Testis: The male gonad containing two functional parts: the SEMINIFEROUS TUBULES for the production and transport of male germ cells (SPERMATOGENESIS) and the interstitial compartment containing LEYDIG CELLS that produce ANDROGENS.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Blotting, Southern: A method (first developed by E.M. Southern) for detection of DNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES.Drosophila Proteins: Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.Fibroblasts: Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.RNA Splice Sites: Nucleotide sequences located at the ends of EXONS and recognized in pre-messenger RNA by SPLICEOSOMES. They are joined during the RNA SPLICING reaction, forming the junctions between exons.Dental Enamel Proteins: The proteins that are part of the dental enamel matrix.Tooth Abnormalities: Congenital absence of or defects in structures of the teeth.Osteomalacia: Disorder caused by an interruption of the mineralization of organic bone matrix leading to bone softening, bone pain, and weakness. It is the adult form of rickets resulting from disruption of VITAMIN D; PHOSPHORUS; or CALCIUM homeostasis.Retina: The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.