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Autosomal recessive ocular albinism associated with a functionally significant tyrosinase gene polymorphism
K Fukai1, S A Holmes, N J Lucchese
1Department of Medical Genetics and Pediatrics, University of Wisconsin, Madison 53706.
Nature Genetics
|January 1, 1995
Summary
Autosomal recessive ocular albinism (AROA) involves reduced eye pigmentation and vision issues. Certain tyrosinase (TYR) gene mutations cause a mild form of OCA1, affecting fetal development but not postnatal skin/hair color.
Area of Science:
- Genetics
- Ophthalmology
- Biochemistry
Background:
- Autosomal recessive ocular albinism (AROA) is characterized by ocular hypopigmentation, foveal hypoplasia, and nystagmus.
- Skin and hair pigmentation are typically normal or slightly lighter than in unaffected relatives.
Observation:
- Analysis of 12 unrelated AROA patients revealed tyrosinase (TYR) gene abnormalities in two individuals.
- These patients were compound heterozygotes for a pathogenic mutation and a common polymorphism (Arg402Gln).
Findings:
- The Arg402Gln polymorphism leads to a tyrosinase polypeptide with reduced thermal stability.
- This suggests that AROA in these cases represents a mild form of Oculocutaneous Albinism type 1 (OCA1).
Implications:
- The condition results from decreased tyrosinase activity during fetal development, causing visual deficits.
- Postnatal skin and hair pigmentation remain unaffected, distinguishing it from classical OCA1.