Sequence analysis of tyrosinase gene in ocular and oculocutaneous albinism patients: introducing three novel mutations

Abstract

Purpose: Albinism is a heterogeneous genetic disorder of melanin synthesis that results in hypopigmented eyes (in patients with ocular albinism) or hair, skin, and eyes (in individuals with oculocutaneous albinism). It is associated with decreased visual acuity, nystagmus, strabismus, and photophobia. The tyrosinase gene is known to be involved in both oculocutaneous albinism and autosomal recessive ocular albinism. In this study, we aimed to screen the mutations in the TYR gene in the nonsyndromic OCA and autosomal recessive ocular albinism patients from Iran.

Methods: The tyrosinase gene was examined in 23 unrelated patients with autosomal recessive ocular albinism or nonsyndromic OCA using DNA sequencing and bioinformatics analysis.

Results: TYR gene mutations were identified in 14 (app. 60%) albinism patients.

Conclusions: We found 10 mutations, 3 of which were novel. No mutation was found in our ocular albinism patients, but one of them was heterozygous for the p.R402Q polymorphism.

Figure 1

The pedigree of patient 4. The nonpathogenic nature of p.R402Q and p.S192Y can be inferred from the above pedigree in which the patient’s parents do not show any albinism features.

Figure 2

The pedigree of patient 9. p.S192Y is not pathogenic in heterozygous form in combination with p.R239W or p.M332I in the patient’s parents.

Figure 3

The pedigree of patient 15. Both p.S192Y and p.R402Q together with the p.G47S are not pathogenic in the patient’s father according to the above pedigree.