Gene TYR
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Also known as
Tyrosinase, OCA1, SHEP3Overview
TYR (Tyrosinase) encodes the enzyme tyrosinase, which catalyzes the rate-limiting step in melanin biosynthesis. Tyrosinase converts tyrosine to DOPA and then to dopaquinone, initiating the complex biochemical pathway that produces melanin pigments in melanocytes. These pigments are responsible for the coloration of skin, hair, and eyes, and provide crucial protection against ultraviolet radiation damage.Mutations in TYR are the most common cause of oculocutaneous albinism type 1 (OCA1), an autosomal recessive disorder characterized by reduced or absent melanin production. Complete loss of tyrosinase activity results in OCA1A, featuring white hair, very pale skin, and light-colored irises throughout life. Partial enzyme activity causes OCA1B, with some pigment accumulation over time. Both forms are associated with visual impairments including nystagmus, photophobia, and reduced visual acuity due to abnormal retinal development.
Beyond albinism, genetic variants in TYR influence normal variation in skin, hair, and eye color across populations. Understanding TYR genetics is important for assessing skin cancer risk, as reduced melanin production increases UV sensitivity, and for genetic counseling regarding pigmentation disorders and their associated health implications.