Retinitis pigmentosa: A Case Report with Thr17Arg as a Novel Mutation in RHO Gene.

Retinitis pigmentosa (RP) is the most common type of inherited progressive photoreceptor cells degeneration causing night blindness, progressive reduction of visual field, loss of retinal pigment epithelial function, and ultimately tubular vision and blindness. Retinitis pigmentosa is most commonly inherited in three ways: autosomal dominant, autosomal recessive, or X-linked, although mitochondrial inheritance also occurs. Mutations in the RHO gene are the most widely associated reason with Retinitis pigmentosa (20-30%). This study aims to find Retinitis pigmentosa likely pathogenic mutation in order to Whole Exome sequencing and Sanger confirmation.

 The patient is an 8-year-old child who presented to a physician following reduced vision in low light, decreased night vision, decreased peripheral vision, and blurred vision. Considering the symptoms of Retinitis pigmentosa, which were observed mildly in their paternal grandparents and severely in aunts; the patient's DNA was extracted and used for molecular studying and sequencing.

In the present study, we report a novel likely pathogenic mutation c.50C>G/ p.Thr17Arg in one affected child of a consanguineous family, which occurs in the coding region of RHO. The autosomal dominant inheritance pattern was confirmed by Sanger since the father of our proband was heterozygous for the mutation.

Since date, c.50C>G/ p.Thr17Arg likely pathogenic variant has not been observed or reported globally. This mutation disrupts the function of the RHO protein and impairs the translocation of this transmembrane protein, causing symptoms of Retinitis pigmentosa. According to family history and molecular studies, the inheritance of the gene in the family is AD, and these findings will be very significant for subsequent pregnancies in this family.