A nonsense mutation in C8orf37 linked with retinitis pigmentosa, early macular degeneration, cataract, and myopia in an arRP family from North India

Abstract

Abstract Objective This study aimed at identifying the underlying genetic defect in a consanguineous autosomal recessive retinitis pigmentosa (arRP) (RP-1175) family having RP with early macular degeneration, cataract, and myopia. Methods Whole-exome sequencing (WES) was performed on the DNA of the proband, and variants observed were validated in the rest of the affected and unaffected family members by Sanger sequencing. Different bioinformatics tools were applied to access the pathogenicity of the observed variant. Results A nonsense mutation i.e., c.555G > A (p.Trp185Ter) in C8orf37 in homozygous form, has been identified that segregated with the disease in the affected members. c.555G > A was absent in unaffected family members and in 107 ethnically matched controls, therefore ruling out its possibility of being a polymorphism. Conclusions Present study identifies a nonsense mutation (c.555G > A) at codon 185 in C8orf37 linked with arRP, early macular degeneration, posterior subcapsular cataract, and myopia. The identical mutation has previously been reported in a Pakistani family with isolated RP and in a Chinese family with RP and macular degeneration. This variable expressivity of the identified mutation c.555G > A in C8orf37 in the analyzed Indian family may be attributed to the presence of the modifier alleles. Also, Trp185 might be a mutation hotspot in Asian arRP patients and in the future, p.Trp185Ter in C8orf37 may be tested during initial screening in arRP cases especially belonging to a similar population.

Keywords

• Retinitis pigmentosa
• Macular degeneration
• C8orf37
• Whole-exome sequencing
• Nonsense mutation