X-LINKED JUVENILE RETINOSCHISIS IN A CONSANGUINEOUS FAMILY Phenotypic Variability and Report of a Homozygous Female Patient

Purpose: To describe the phenotypic variability in a consanguineous family with genetically confirmed X-linked retinoschisis. Methods: Five patients, including one homozygous female, were characterized by clinical examination, optical coherence tomography, fundus autofluorescence, mapping of macular pigment optical density, electroretinography, and DNA testing. Results: The 36-year-old male index patient showed a ring of enhanced autofluorescence and outer retinal atrophy on optical coherence tomography. Electroretinography testing revealed a reduced a/b ratio. His mother presented with a central atrophic retina with markedly reduced autofluorescence signal and a surrounding ring of enhanced autofluorescence. The 40-year-old brother of the index patient and his 2 sons showed characteristic signs for X-linked retinoschisis, including retinal schisis and a reduced a/b ratio. Genetic testing revealed a c.293C>A mutation in the RS1 gene in all affected family members while the mother of the index patient was homozygous for this mutation. Conclusion: X-linked retinoschisis can present with a wide phenotypic variability. Here, detailed family history and genetic testing established the diagnosis of X-linked retinoschisis despite striking differences in phenotypic presentation in affected subjects, homozygosity of one affected female, and seemingly dominant inheritance in three subsequent generations because of multiple consanguinity.