Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

X-linked hereditary spastic paraplegias (HSP) present with two distinct phenotypes, pure and complicated. The pure form is characterized by spasticity and gait difficulties but lacks the additional features (nystagmus, dysarthria, mental retardation) present in the complicated form. The complicated form is heterogeneous, caused by mutations of the L1CAM gene at Xq28 (SPG1) or the PLP gene at Xq22 (SPG2) that is allelic to Pelizaeus-Merzbacher disease (PMD). Since in one kindred (K313) the pure form of HSP was also mapped to Xq22, this raises the issue as to whether a pure form of HSP exists that is allelic to X-linked complicated HSP (SPG2) and PMD. To answer this question, we carried out linkage analysis in a new pedigree with pure HSP (K101) and refined linkage in pedigree K313. The PLP gene was also screened for mutation by direct sequencing and reverse-transcriptase polymerase chain reaction (RT-PCR). In both families, the disease locus mapped to Xq22 with Lod scores at zero recombination of 5.3 for COL4A5 2B6 in K313 and 2.4 for DXS101 in K101. A T to C transition in exon 5 of the PLP gene was identified from affected individuals of K313. This transition causes a Ser to Pro mutation in the major extracellular loop of PLP/DM20. This finding demonstrates that a form of X-linked pure spastic paraplegia, X-linked complicated HSP (SPG2) and PMD are allelic disorders. There was no evidence of mutations in either coding sequences or the intron/exon junctions of PLP in pedigree K101, suggesting that the disease-producing mutation may be in the noncoding portions of PLP or in a nearby gene.
 ...
PMID:Refined genetic mapping and proteolipid protein mutation analysis in X-linked pure hereditary spastic paraplegia. 878 Jan 1

A map has been assembled that extends from the XY homology region in Xq21.3 to proximal Xq24, approximately 20 Mb, formatted with 200 STSs that include 25 dinucleotide repeat polymorphic markers and more than 80 expressed sequences including 30 genes. New genes HTRP5, CAPN6, STPK, 14-3-3PKR, and CALM1 and previously known genes including BTK, DDP, GLA, PLP, COL4A5, COL4A6, PAK3, and DCX are localized; candidate loci for other disorders for which genes have not yet been identified, including DFN-2, POF, megalocornea, and syndromic and nonsyndromic mental retardation, are also mapped in the region. The telomeric end of the contig overlaps a yeast artificial chromosome (YAC) contig from Xq24-q26 and with other previously published contigs provides complete sequence-tagged site (STS)/YAC-based coverage of the long arm of the X chromosome. The order of published landmark loci in genetic and radiation hybrid maps is in general agreement. Combined with high-density STS landmarks, the multiple YAC clone coverage and integrated genetic, radiation hybrid, and transcript map provide resources to further disease gene searches and sequencing.
 ...
PMID:Integrated STS/YAC physical, genetic, and transcript map of human Xq21.3 to q23/q24 (DXS1203-DXS1059). 1036 51

Pyridoxal phosphate and pyridoxamine phosphate, the catalytically active forms of vitamin B(6), influence brain function by participating at stages in metabolism of proteins, lipids, carbohydrates, other coenzymes and hormones. Vitamin B(6) participates in the metabolism of amino acids in the form of decarboxylation, transamination, deamination, racemization and desulfhydration reactions. The crucial roles that these coenzymes play in the maintenance of functional integrity of the brain become evident when one realizes that some compounds implicated as neurotransmitters are synthesized and/or metabolized by the aid of the vitamin B(6)-dependent enzymatic reactions. These include dopamine, norepinephrine and serotonin, tyramine, tryptamine, taurine, histamine, gamma aminobutyric acid, and even acetylcholine indirectly. In recent years, the above-mentioned biogenic amines have become of considerable interest to neurobiologists who are investigating the etiology and the pathological manifestations of many disorders of the central nervous system such as Parkinsonism, Huntington's chorea, minimal brain disfunction, schizophrenia, depression, sleep disorders and seizure disorders. Vitamin B(6) deficiency in these cases is characterized by anemia, growth retardation and alteration in neuronal function, including neuropathies, hyperirritability, hyperexcitability and convulsions. The importance of vitamin B(6) in the study of brain function assumes still greater significance when one considers the effects of nutritional deficiencies on growth and development of the brain and mental processes and in the involvement of vitamin B(6) in some inborn errors of metabolism which result in mental retardation. Vitamin B(6) deficiency results in a lowered concentration of Coenzyme A in blood, in reduced absorption and storage of vitamin B(12), and in increased excretion of vitamin C. Furthermore, vitamin B(6) acts synergistically with vitamin E to control metabolism of unsaturated fats, with vitamin C in tyrosine metabolism and with niacin in its action and participates in niacin synthesis. In addition, vitamin B(6) deficiency results in insufficiency of insulin and in alteration of the functions of adrenal and pituitary glands, since it is involved in the synthesis of growth hormone, follicle-stimulating hormone, luteinizing hormone, aldosterone, glucagon, cortisol, estradiol, testosterone and epinephrine. It is hoped that by understanding the factors that regulate the synthesis, binding, storage and degradation of pyridoxal phosphate in the brain, a better insight into the role of vitamin B(6) in neurobiology may be gained.
 ...
PMID:Regulation and function of pyridoxal phosphate in CNS. 1964 63