Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0268494 (ATN)
 694 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of the visible pigment melanin by the melanocyte cell is the basis of the human pigmentary system, those genes directing the formation, transport and distribution of the specialised melanosome organelle in which melanin accumulates can legitimately be called pigmentation genes. The genes involved in this process have been identified through comparative genomic studies of mouse coat colour mutations and by the molecular characterisation of human hypopigmentary genetic diseases such as OCA1 and OCA2. The melanocyte responds to the peptide hormones alpha-MSH or ACTH through the MC1R G-protein coupled receptor to stimulate melanin production through induced maturation or switching of melanin type. The pheomelanosome, containing the key enzyme of the pathway tyrosinase, produces light red/yellowish melanin, whereas the eumelanosome produces darker melanins via induction of additional TYRP1, TYRP2, SILV enzymes, and the P-protein. Intramelanosomal pH governed by the P-protein may act as a critical determinant of tyrosinase enzyme activity to control the initial step in melanin synthesis or TYRP complex formation to facilitate melanogenesis and melanosomal maturation. The search for genetic variation in these candidate human pigmentation genes in various human populations has revealed high levels of polymorphism in the MC1R locus, with over 30 variant alleles so far identified. Functional correlation of MC1R alleles with skin and hair colour provides evidence that this receptor molecule is a principle component underlying normal human pigment variation.
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PMID:Human pigmentation genes: identification, structure and consequences of polymorphic variation. 1160 44

Oculocutaneous albinism (OCA) is a genetically heterogeneous group of disorders characterized by absent or reduced pigmentation of the skin, hair, and eyes. In humans, four genes have been associated with "classical" OCA and another 12 genes with syndromic forms of OCA. To assess the prevalence of different forms of OCA and different gene mutations among non-Hispanic Caucasian patients, we performed DNA sequence analysis of the four genes associated with "classical" OCA (TYR, OCA2, TYRP1, SLC45A2), the two principal genes associated with syndromic OCA (HPS1, HPS4), and a candidate OCA gene (SILV), in 121 unrelated, unselected non-Hispanic/Latino Caucasian patients carrying the clinical diagnosis of OCA. We identified apparent pathologic TYR gene mutations in 69% of patients, OCA2 mutations in 18%, SLC45A2 mutations in 6%, and no apparent pathological mutations in 7% of patients. We found no mutations of TYRP1, HPS1, HPS4, or SILV in any patients. Although we observed a diversity of mutations for each gene, a relatively small number of different mutant alleles account for a majority of the total. This study demonstrates that, contrary to long-held clinical lore, OCA1, not OCA2, is by far the most frequent cause of OCA among Caucasian patients.
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PMID:Comprehensive analysis of oculocutaneous albinism among non-Hispanic caucasians shows that OCA1 is the most prevalent OCA type. 1846 83