Charcot-Marie-Tooth Disease: A hereditary motor and sensory neuropathy transmitted most often as an autosomal dominant trait and characterized by progressive distal wasting and loss of reflexes in the muscles of the legs (and occasionally involving the arms). Onset is usually in the second to fourth decade of life. This condition has been divided into two subtypes, hereditary motor and sensory neuropathy (HMSN) types I and II. HMSN I is associated with abnormal nerve conduction velocities and nerve hypertrophy, features not seen in HMSN II. (Adams et al., Principles of Neurology, 6th ed, p1343)Myelin P0 Protein: A protein that accounts for more than half of the peripheral nervous system myelin protein. The extracellular domain of this protein is believed to engage in adhesive interactions and thus hold the myelin membrane compact. It can behave as a homophilic adhesion molecule through interactions with its extracellular domains. (From J Cell Biol 1994;126(4):1089-97)Sural Nerve: A branch of the tibial nerve which supplies sensory innervation to parts of the lower leg and foot.Myelin Proteins: MYELIN-specific proteins that play a structural or regulatory role in the genesis and maintenance of the lamellar MYELIN SHEATH structure.Hereditary Sensory and Motor Neuropathy: A group of slowly progressive inherited disorders affecting motor and sensory peripheral nerves. Subtypes include HMSNs I-VII. HMSN I and II both refer to CHARCOT-MARIE-TOOTH DISEASE. HMSN III refers to hypertrophic neuropathy of infancy. HMSN IV refers to REFSUM DISEASE. HMSN V refers to a condition marked by a hereditary motor and sensory neuropathy associated with spastic paraplegia (see SPASTIC PARAPLEGIA, HEREDITARY). HMSN VI refers to HMSN associated with an inherited optic atrophy (OPTIC ATROPHIES, HEREDITARY), and HMSN VII refers to HMSN associated with retinitis pigmentosa. (From Adams et al., Principles of Neurology, 6th ed, p1343)Chromosomes, Human, Pair 17: A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.Neural Conduction: The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.Glycine-tRNA Ligase: An enzyme that activates glycine with its specific transfer RNA. 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.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.Schwann Cells: Neuroglial cells of the peripheral nervous system which form the insulating myelin sheaths of peripheral axons.Connexins: A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions.Foot Deformities: Alterations or deviations from normal shape or size which result in a disfigurement of the foot.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.Peripheral Nerves: The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.Neoprene: An oil-resistant synthetic rubber made by the polymerization of chloroprene.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.Demyelinating Diseases: Diseases characterized by loss or dysfunction of myelin in the central or peripheral nervous system.Muscular Atrophy: Derangement in size and number of muscle fibers occurring with aging, reduction in blood supply, or following immobilization, prolonged weightlessness, malnutrition, and particularly in denervation.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Neurofilament Proteins: Type III intermediate filament proteins that assemble into neurofilaments, the major cytoskeletal element in nerve axons and dendrites. They consist of three distinct polypeptides, the neurofilament triplet. Types I, II, and IV intermediate filament proteins form other cytoskeletal elements such as keratins and lamins. It appears that the metabolism of neurofilaments is disturbed in Alzheimer's disease, as indicated by the presence of neurofilament epitopes in the neurofibrillary tangles, as well as by the severe reduction of the expression of the gene for the light neurofilament subunit of the neurofilament triplet in brains of Alzheimer's patients. (Can J Neurol Sci 1990 Aug;17(3):302)Myokymia: Successive and rapid contractions of motor units associated with chronic nerve injury. The discharges arise from the peripheral aspects of regenerating nerves, and clinically impart a nearly continuous undulation of the body surface overlying the muscle. (Adams et al., Principles of Neurology, 6th ed, p1491)Genes, Recessive: Genes that influence the PHENOTYPE only in the homozygous state.Genes, Dominant: Genes that influence the PHENOTYPE both in the homozygous and the heterozygous state.Foot Deformities, Acquired: Distortion or disfigurement of the foot, or a part of the foot, acquired through disease or injury after birth.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Muscle Weakness: A vague complaint of debility, fatigue, or exhaustion attributable to weakness of various muscles. The weakness can be characterized as subacute or chronic, often progressive, and is a manifestation of many muscle and neuromuscular diseases. (From Wyngaarden et al., Cecil Textbook of Medicine, 19th ed, p2251)GTP Phosphohydrolases: Enzymes that hydrolyze GTP to GDP. EC 3.6.1.-.Sciatic Nerve: A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.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)Peripheral Nervous System Diseases: Diseases of the peripheral nerves external to the brain and spinal cord, which includes diseases of the nerve roots, ganglia, plexi, autonomic nerves, sensory nerves, and motor nerves.Alanine-tRNA Ligase: An enzyme that activates alanine with its specific transfer RNA. EC Linkage: The co-inheritance of two or more non-allelic GENES due to their being located more or less closely on the same CHROMOSOME.Tendon Transfer: Surgical procedure by which a tendon is incised at its insertion and placed at an anatomical site distant from the original insertion. The tendon remains attached at the point of origin and takes over the function of a muscle inactivated by trauma or disease.DNA Mutational Analysis: Biochemical identification of mutational changes in a nucleotide sequence.Consanguinity: The magnitude of INBREEDING in humans.Dynamin II: A subtype of dynamin found ubiquitously expressed in a variety of tissues.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.Mitochondrial Proteins: Proteins encoded by the mitochondrial genome or proteins encoded by the nuclear genome that are imported to and resident in the MITOCHONDRIA.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.Point 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.Mice, Neurologic Mutants: Mice which carry mutant genes for neurologic defects or abnormalities.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."Age of Onset: The age, developmental stage, or period of life at which a disease or the initial symptoms or manifestations of a disease appear in an individual.Gene Duplication: Processes occurring in various organisms by which new genes are copied. Gene duplication may result in a MULTIGENE FAMILY; supergenes or PSEUDOGENES.Foot: The distal extremity of the leg in vertebrates, consisting of the tarsus (ANKLE); METATARSUS; phalanges; and the soft tissues surrounding these bones.Wallerian Degeneration: Degeneration of distal aspects of a nerve axon following injury to the cell body or proximal portion of the axon. The process is characterized by fragmentation of the axon and its MYELIN SHEATH.Genetic Markers: A phenotypically recognizable genetic trait which can be used to identify a genetic locus, a linkage group, or a recombination event.Muscular Atrophy, Spinal: A group of disorders marked by progressive degeneration of motor neurons in the spinal cord resulting in weakness and muscular atrophy, usually without evidence of injury to the corticospinal tracts. Diseases in this category include Werdnig-Hoffmann disease and later onset SPINAL MUSCULAR ATROPHIES OF CHILDHOOD, most of which are hereditary. (Adams et al., Principles of Neurology, 6th ed, p1089)Ranvier's Nodes: Regularly spaced gaps in the myelin sheaths of peripheral axons. Ranvier's nodes allow saltatory conduction, that is, jumping of impulses from node to node, which is faster and more energetically favorable than continuous conduction.Nerve Fibers, Myelinated: A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.Chromosome Mapping: Any method used for determining the location of and relative distances between genes on a chromosome.Gait Disorders, Neurologic: Gait abnormalities that are a manifestation of nervous system dysfunction. These conditions may be caused by a wide variety of disorders which affect motor control, sensory feedback, and muscle strength including: CENTRAL NERVOUS SYSTEM DISEASES; PERIPHERAL NERVOUS SYSTEM DISEASES; NEUROMUSCULAR DISEASES; or MUSCULAR DISEASES.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.