Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The eye of a 47 year old man with tyrosinase-positive oculocutaneous albinism, photophobia, nystagmus and visual acuity 0, 4-0, 5 was histologically examined after orbital exenteration for neoplasia. Histologic serial sections of the centre of the retina showed a continuous 6-8 cell-layer of ganglion cells, without any suggestion of a foveolar pit. The outer layers of the macular retina were altered secondarily by tumor-impression-folds; they were unremarkable at the periphery as were the acid mucopolysaccharides in the receptor region. Electron microscopy of the uvea and the retinal pigment epithelium showed a normal number of pigment granules but a deficiency of melanin, as well as structural anomalies. The absence of the foveolar pit and the decrease of visual acuity in tyrosinase-positive albinism is caused by definite morphologic alteration in the arrangement of ganglion cells in the macular region in the sense of a foveolar aplasia. The etiology is discussed. An identic anomaly has been described in aniridia, similar ones in other congenital ocular diseases.
 ...
PMID:[Foveolar aplasia in tyrosinase-positive oculocutaneous albinisim (author's transl)]. 82 41

Nine patients with Prader-Willi syndrome (five female and four male; one Oriental and eight white), all of whom had interstitial deletions of the proximal long arm of one chromosome 15 (q11-q13) were found to have decreased tyrosinase activity in isolated hair bulbs. As infants, all patients had light hair and skin coloring, both of which darkened with age. Light and electron microscopic analysis of skin and hair bulbs disclosed a reduced number of melanocytes in the basal epidermis and hair bulbs. Each patient demonstrated decreased pigmentation of the iris stroma, which was accentuated peripherally and manifested clinically as iris translucency. There was no foveal hypoplasia, nystagmus, or photophobia, and ocular function was normal. Oculocutaneous albinoidism is thus a component of del(15q) Prader-Willi syndrome with reduction of melanocytes of neural crest origin (skin, hair, and iris stroma) and retention of normal retinal and iris pigment epithelia of neuroectodermal origin.
 ...
PMID:Oculocutaneous albinoidism as a manifestation of reduced neural crest derivatives in the Prader-Willi syndrome. 681 26

Oculocutaneous albinism comprises hereditary disorders in which there is a congenital absence or reduction of melanin in the skin, hair and eyes, coupled with nystagmus, photophobia and reduced visual acuity. The body is unable to make melanin (a compound derived from the metabolism of tyrosine) due to the functional absence of the enzyme tyrosinase. The disease is transmitted as an autosomal recessive character. In man, there are six conditions distinguishable in relation to their frequency, and their clinical, biochemical, ultrastructural, and genetic characteristics. The attempt to identify the heterozygote has led to contradictory results. Abnormal transparency of the iris has only been observed in some heterozygotes, and this feature cannot be used to recognise carriers. As far as treatment is concerned, the two main problems are sensitivity to sunlight, with concomitant susceptibility to skin tumors, and collateral vision disturbances. Subjects should avoid direct sunlight. Photophobia can be reduced by wearing sunglasses.
 ...
PMID:[Oculo-cutaneous albinism in man. Biochemical, genetic, clinical, and population aspects]. 688 87

An apparently recessively inherited albinism variant characterized by skin tanning, light but not white hair, uniformly pigmented irides varying in colour from hazel to dark brown, slight nystagmus, divergent strabismus, mild hyperkeratosis and only slight or absent photophobia, occurs among the Elema-speaking peoples of the Gulf Province of Papua New Guinea at frequencies indicating that the gene which produces it is polymorphic. It is readily distinguishable from both classical types of albinism, from the "redskin" variant also found in Papua New Guinea, and from the "yellow mutant" albinism of North America. The differences from the African types of "albinoidism" or "partial albinism" are less marked, and it may represent a similar mutation with simply a different distribution of the melanosomes in the two peoples, Allelism, or lack of it, with classical tyrosinase-positive albinism has not been determined.
 ...
PMID:A high-frequency albinism variant on the gulf coast of Papua. 694 71

A 9-year-old Caucasian girl of northern European ancestry presented with findings suggestive of ocular albinism, although she maintains good visual acuity and lacks nystagmus and photophobia. DNA analysis revealed that the patient is a compound heterozygote for mutations in the tyrosinase gene, which is typically associated with overt, generalized oculocutaneous albinism and severe ocular symptoms. Her particular genotype confers no apparent cutaneous disease and only mild ocular features.
 ...
PMID:Ocular albinism with absent foveal pits but without nystagmus, photophobia, or severely reduced vision. 2000 30

Oculocutaneous albinism (OCA) is an autosomal recessive disorder characterized by either complete lack of or a reduction in melanin biosynthesis in the skin, hair, and eyes. OCA1, the most common and severe type, is caused by mutations in the tyrosinase (TYR) gene. In this study, we report a Chinese family with two members affected by OCA. Blood samples were collected from all family members. Genomic DNA was isolated from blood leukocytes, and all coding exons and adjacent intronic sequences of the TYR gene were examined for mutation analysis using polymerase chain reaction (PCR)-based sequencing. A pedigree chart was drawn, and clinical examinations and paraclinical tests were performed. Compound heterozygous mutations in TYR (c.832C>T and c.929_930insC, which resulted in p.Arg278* and p.Arg311Lysfs*7, respectively) were identified in the two patients with milky skin, white hair, photophobia, and reduced visual acuity, while other family members only carried one of two heterozygous mutations. In addition, a homozygous missense mutation c.814G>A (p.Glu272Lys) in the solute carrier family 45 member 2 (SLC45A2) gene was found in both patients and unaffected family members, suggesting that this may not be a causative mutation. The findings of this study expand the mutational spectrum of OCA. Compound heterozygous mutations (c.832C>T and c.929_930insC) in the TYR gene may be responsible for partial clinical manifestations of OCA, while the homozygous missense mutation c.814G>A (p.Glu272Lys) in the SLC45A2 gene may not be associated with OCA.
 ...
PMID:Mutation analysis of a Chinese family with oculocutaneous albinism. 2782 21