Decoding of tyrosinase leads to albinism in a nonidentical twin

Oculocutaneous albinism (OCA) is an autosomal recessive disorder, phenotypically subcategorized as OCA subtype 1A (OCA-1A) and OCA subtype 1B (OCA-1B). Both the subtypes are genetically caused by the mutations in the tyrosinase (TYR) gene. A 6-month-old nonidentical twin sister was albino who was diagnosed with OCA-1A and had clinical features including hypopigmentation in iris, lid, lashes, skin, nystagmus, and albinotic fundus. Genetic screening revealed the pathogenic mutation at TYR gene locus in albino child, whereas the other child was carrier and holding normal phenotype. We report a differential TYR expression pattern on one of the nonidentical twins.