Identification of Novel Nonsense <i>RPGR</i> Variant Causing Mild X-Linked Cone-Rod Dystrophy and Myopia

Background: Mutations in the RPGR gene are associated with rod-cone or cone-rod dystrophy, latter mutations at distal end. Cone-rod dystrophy (CRD) is a subgroup of hereditary retinal disorders characterized by primary degeneration cone photoreceptors often followed progressive loss rod peripheral visual field. Purpose: The aim this study was to describe milder CRD phenotype novel pathogenic variant c.1905 + 223C > T (p.Q710X) found which results shortening photoreceptor specific isoform ORF15. Method: An 11-year-old boy symptoms and two female relatives were referred for detailed ophthalmic examinations. Genetic testing performed next-generation sequencing clinical exome Sanger segregation analysis. Results: analysis identified ORF15 (c.1905 T, p.Q710X) proband considered as according American College Medical Genetics Genomics (ACMG) standards. Segregation mutation heterozygous state mother her sister. Detailed ophthalmological examination revealed slightly reduced color vision scattered grayish point-like deposits posterior pole fundus male patient. All carriers myopic. Conclusion: We report Bulgarian patient features compatible diagnosis. This condition inherited an X-linked dominant trait its familial form presenting mild hemizygous moderate high myopia carriers.