Canavan Disease: A rare neurodegenerative condition of infancy or childhood characterized by white matter vacuolization and demeylination that gives rise to a spongy appearance. Aspartoacylase deficiency leads to an accumulation of N-acetylaspartate in astrocytes. Inheritance may be autosomal recessive or the illness may occur sporadically. This illness occurs more frequently in individuals of Ashkenazic Jewish descent. The neonatal form features the onset of hypotonia and lethargy at birth, rapidly progressing to coma and death. The infantile form features developmental delay, DYSKINESIAS, hypotonia, spasticity, blindness, and megalencephaly. The juvenile form is characterized by ATAXIA; OPTIC ATROPHY; and DEMENTIA. (From Adams et al., Principles of Neurology, 6th ed, p944; Am J Med Genet 1988 Feb;29(2):463-71)beta-Hexosaminidase alpha Chain: The alpha subunit of hexosaminidase A. Mutations in the gene that encodes this protein can result in loss of hexosaminidase A activity and are linked to TAY-SACHS DISEASE.AmidohydrolasesJews: An ethnic group with historical ties to the land of ISRAEL and the religion of JUDAISM.Aspartic Acid: One of the non-essential amino acids commonly occurring in the L-form. It is found in animals and plants, especially in sugar cane and sugar beets. It may be a neurotransmitter.Leukodystrophy, Metachromatic: An autosomal recessive metabolic disease caused by a deficiency of CEREBROSIDE-SULFATASE leading to intralysosomal accumulation of cerebroside sulfate (SULFOGLYCOSPHINGOLIPIDS) in the nervous system and other organs. Pathological features include diffuse demyelination, and metachromatically-staining granules in many cell types such as the GLIAL CELLS. There are several allelic and nonallelic forms with a variety of neurological symptoms.Saudi ArabiaEurope, EasternAphorisms and Proverbs as Topic: Short popular sayings effectively expressing or astutely professing general truths or useful thoughts. (From Random House Unabridged Dictionary, 2d ed, p97, p1556)LithuaniaLithium: An element in the alkali metals family. It has the atomic symbol Li, atomic number 3, and atomic weight [6.938; 6.997]. Salts of lithium are used in treating BIPOLAR DISORDER.Lithium Compounds: Inorganic compounds that contain lithium as an integral part of the molecule.Myelin Sheath: The lipid-rich sheath surrounding AXONS in both the CENTRAL NERVOUS SYSTEMS and PERIPHERAL NERVOUS SYSTEM. The myelin sheath is an electrical insulator and allows faster and more energetically efficient conduction of impulses. The sheath is formed by the cell membranes of glial cells (SCHWANN CELLS in the peripheral and OLIGODENDROGLIA in the central nervous system). Deterioration of the sheath in DEMYELINATING DISEASES is a serious clinical problem.Tay-Sachs Disease: An autosomal recessive neurodegenerative disorder characterized by the onset in infancy of an exaggerated startle response, followed by paralysis, dementia, and blindness. It is caused by mutation in the alpha subunit of the HEXOSAMINIDASE A resulting in lipid-laden ganglion cells. It is also known as the B variant (with increased HEXOSAMINIDASE B but absence of hexosaminidase A) and is strongly associated with Ashkenazic Jewish ancestry.Hexosaminidase A: A mammalian beta-hexosaminidase isoform that is a heteromeric protein comprized of both hexosaminidase alpha and hexosaminidase beta subunits. Deficiency of hexosaminidase A due to mutations in the gene encoding the hexosaminidase alpha subunit is a case of TAY-SACHS DISEASE. Deficiency of hexosaminidase A and HEXOSAMINIDASE B due to mutations in the gene encoding the hexosaminidase beta subunit is a case of SANDHOFF DISEASE.Area Health Education Centers: Education centers authorized by the Comprehensive Health Manpower Training Act, 1971, for the training of health personnel in areas where health needs are the greatest. May be used for centers other than those established by the United States act.beta-N-Acetylhexosaminidases: A hexosaminidase specific for non-reducing N-acetyl-D-hexosamine residues in N-acetyl-beta-D-hexosaminides. It acts on GLUCOSIDES; GALACTOSIDES; and several OLIGOSACCHARIDES. Two specific mammalian isoenzymes of beta-N-acetylhexoaminidase are referred to as HEXOSAMINIDASE A and HEXOSAMINIDASE B. Deficiency of the type A isoenzyme causes TAY-SACHS DISEASE, while deficiency of both A and B isozymes causes SANDHOFF DISEASE. The enzyme has also been used as a tumor marker to distinguish between malignant and benign disease.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)Information Centers: Facilities for collecting and organizing information. They may be specialized by subject field, type of source material, persons served, location, or type of services.Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.Rare Diseases: A large group of diseases which are characterized by a low prevalence in the population. They frequently are associated with problems in diagnosis and treatment.National Health Planning Information Center (U.S.): A center in the HEALTH RESOURCES ADMINISTRATION Division of Planning Methods and Technology which provides access to current information on health planning and resources development.Current Procedural Terminology: Descriptive terms and identifying codes for reporting medical services and procedures performed by PHYSICIANS. It is produced by the AMERICAN MEDICAL ASSOCIATION and used in insurance claim reporting for MEDICARE; MEDICAID; and private health insurance programs (From CPT 2002).Spain: Parliamentary democracy located between France on the northeast and Portugual on the west and bordered by the Atlantic Ocean and the Mediterranean Sea.Treponema pallidum: The causative agent of venereal and non-venereal syphilis as well as yaws.Fellowships and Scholarships: Stipends or grants-in-aid granted by foundations or institutions to individuals for study.Leukodystrophy, Globoid Cell: An autosomal recessive metabolic disorder caused by a deficiency of GALACTOSYLCERAMIDASE leading to intralysosomal accumulation of galactolipids such as GALACTOSYLCERAMIDES and PSYCHOSINE. It is characterized by demyelination associated with large multinucleated globoid cells, predominantly involving the white matter of the central nervous system. The loss of MYELIN disrupts normal conduction of nerve impulses.Cerebroside-Sulfatase: An enzyme that catalyzes the hydrolysis of cerebroside 3-sulfate (sulfatide) to yield a cerebroside and inorganic sulfate. A marked deficiency of arylsulfatase A, which is considered the heat-labile component of cerebroside sulfatase, has been demonstrated in all forms of metachromatic leukodystrophy (LEUKODYSTROPHY, METACHROMATIC). EC Loss: A general term for the complete or partial loss of the ability to hear from one or both ears.N-Acylsphingosine Galactosyltransferase: An enzyme that catalyzes the conversion of UDP-galactose and N-acylsphingosine to D-galactosylceramide and UDP.Psychosine: An intermediate in the biosynthesis of cerebrosides. It is formed by reaction of sphingosine with UDP-galactose and then itself reacts with fatty acid-Coenzyme A to form the cerebroside.Food Additives: Substances which are of little or no nutritive value, but are used in the processing or storage of foods or animal feed, especially in the developed countries; includes ANTIOXIDANTS; FOOD PRESERVATIVES; FOOD COLORING AGENTS; FLAVORING AGENTS; ANTI-INFECTIVE AGENTS (both plain and LOCAL); VEHICLES; EXCIPIENTS and other similarly used substances. Many of the same substances are PHARMACEUTIC AIDS when added to pharmaceuticals rather than to foods.Neurologic Examination: Assessment of sensory and motor responses and reflexes that is used to determine impairment of the nervous system.Dyssomnias: A broad category of sleep disorders characterized by either hypersomnolence or insomnia. The three major subcategories include intrinsic (i.e., arising from within the body) (SLEEP DISORDERS, INTRINSIC), extrinsic (secondary to environmental conditions or various pathologic conditions), and disturbances of circadian rhythm. (From Thorpy, Sleep Disorders Medicine, 1994, p187)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)Egypt: A country in northern Africa, bordering the Mediterranean Sea, between Libya and the Gaza Strip, and the Red Sea north of Sudan, and includes the Asian Sinai Peninsula Its capital is Cairo.Los AngelesIntelligence: The ability to learn and to deal with new situations and to deal effectively with tasks involving abstractions.Founder Effect: A phenomenon that is observed when a small subgroup of a larger POPULATION establishes itself as a separate and isolated entity. The subgroup's GENE POOL carries only a fraction of the genetic diversity of the parental population resulting in an increased frequency of certain diseases in the subgroup, especially those diseases known to be autosomal recessive.Factor XI Deficiency: A hereditary deficiency of blood coagulation factor XI (also known as plasma thromboplastin antecedent or PTA or antihemophilic factor C) resulting in a systemic blood-clotting defect called hemophilia C or Rosenthal's syndrome, that may resemble classical hemophilia.Intelligence Tests: Standardized tests that measure the present general ability or aptitude for intellectual performance.Spider Bites: The effects, both local and systemic, caused by the bites of SPIDERS.Brown Recluse Spider: A spider of the genus Loxosceles, found in the midwestern and other parts of the United States, which carries a hemolytic venom that produces local necrosis or ulceration.Spiders: Arthropods of the class ARACHNIDA, order Araneae. Except for mites and ticks, spiders constitute the largest order of arachnids, with approximately 37,000 species having been described. The majority of spiders are harmless, although some species can be regarded as moderately harmful since their bites can lead to quite severe local symptoms. (From Barnes, Invertebrate Zoology, 5th ed, p508; Smith, Insects and Other Arthropods of Medical Importance, 1973, pp424-430)Spider Venoms: Venoms of arthropods of the order Araneida of the ARACHNIDA. The venoms usually contain several protein fractions, including ENZYMES, hemolytic, neurolytic, and other TOXINS, BIOLOGICAL.Dapsone: A sulfone active against a wide range of bacteria but mainly employed for its actions against MYCOBACTERIUM LEPRAE. Its mechanism of action is probably similar to that of the SULFONAMIDES which involves inhibition of folic acid synthesis in susceptible organisms. It is also used with PYRIMETHAMINE in the treatment of malaria. (From Martindale, The Extra Pharmacopoeia, 30th ed, p157-8)Diagnostic Errors: Incorrect diagnoses after clinical examination or technical diagnostic procedures.Phosphoric Diester Hydrolases: A class of enzymes that catalyze the hydrolysis of one of the two ester bonds in a phosphodiester compound. EC 3.1.4.Gynecological Examination: Inspection and PALPATATION of female breasts, abdomen, and GENITALIA, as well as obtaining a gynecological history. (from Dictionary of Obstetrics and Gynecology)Pregnancy Tests: Tests to determine whether or not an individual is pregnant.Prenatal Diagnosis: Determination of the nature of a pathological condition or disease in the postimplantation EMBRYO; FETUS; or pregnant female before birth.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Pregnancy Tests, Immunologic: Methods of detecting pregnancy by examining the levels of human chorionic gonadotropin (HCG) in plasma or urine.Chorionic Villi Sampling: A method for diagnosis of fetal diseases by sampling the cells of the placental chorionic villi for DNA analysis, presence of bacteria, concentration of metabolites, etc. The advantage over amniocentesis is that the procedure can be carried out in the first trimester.Pregnancy Trimester, Second: The middle third of a human PREGNANCY, from the beginning of the 15th through the 28th completed week (99 to 196 days) of gestation.