Retinal mosaicism in a girl with an X–Y translocation

To the Editor X-linked ocular albinism is a common disorder of melanosome biogenesis. 1 In affected male subjects, it manifests in the form of reduced visual acuity, infantile nystagmus and ocular hypopigmentation. 1 Carrier female subjects are minimally affected but may show iris translumination and coarse pattern of blotchy hypopigmentation and hyperpigmentation of the retinal pigment epithelium due to lyonisation. 2 3 X-linked ocular albinism is caused by mutations in the G protein-coupled receptor 143 (GPR143) gene, also known as the ocular albinism 1 gene located at Xp22.32. 1 About 48% of reported mutations in the GPR143 gene are intragenic deletions and about 43% are point mutations. 4 Case report We examined a 3-year-old girl with chromosome abnormality in form of X: