Identification of a novel mutation (p.Ile198Thr) in gene TYR in a Pakistani family with nonsyndromic oculocutaneous albinism.

[oculocutaneous albinism]

The TYR gene (MIM #6069333 ) is located at position 11 q 14 .3 on the human chromosome , and encodes tyrosinase , which is expressed in melanocytes and controls the biosynthesis of melanin . Most TYR mutations eliminate the activity of tyrosinase , preventing melanocytes from producing any melanin throughout life . People with this form of albinism have white hair , light-coloured eyes and very pale skin . Some mutations in TYR reduce but do not completely eliminate tyrosinase activity , and allow some melanin to be produced . We report a Pakistani family with four members affected by oculocutaneous albinism (OCA ). Blood samples were collected from all affected individuals , normal siblings and their parents . Genomic DNA was extracted , and sequence analysis of all the coding exons and adjacent intronic sequences of TYR was performed , which identified a novel missense substitution (p .Ile 198 Thr ). Sequencing of TYR in 90 unrelated healthy individuals showed no sequence variant at this location . Our study expands the mutational spectrum of OCA 1 .