A Novel Arg120Pro Mutation in the RP2 Gene in an Iranian Family with X-linked Retinitis Pigmentosa: A Case Report

As the most common type of inherited retinal degenerative disease, retinitis pigmentosa (RP) has taken clinical and prenatal attention. Considering the clinical importance of consanguineous marriages, new mutations in this type of pregnancy have a high risk and increase the importance of Prenatal Diagnosis (PND). In vitro analysis was done through Whole Exome Sequencing (WES) for a 36-year-old woman who was referred to a genetic laboratory in Kermanshah in 2021 for PND. The woman had consanguineous marriage and was pregnant with twins (a boy and a girl). Mutation confirmation tests were also performed on her husband and both fetuses to find mutations. Moreover, in silico analyses were performed by SWISS-MODEL, ProSA, Molprobity, Swiss-Pdb Viewer, and ERRAT. The WES analysis showed a novel mutation of the RP2 gene (exon2:c. 359G>C: p.R120P) in the 36-year-old pregnant woman. Mutations identified in her husband and her twins revealed changes in protein conformations. Further modeling and validation evaluations showed the replacement of Arg by Pro at the 120^th residue site of the cognate protein. For the first time, our report introduced a novel missense mutation in the RP2 gene associated with severe signs of RP in an Iranian family based on an X-linked recessive pattern of genetic inheritance. These findings may pave the way for a better diagnosis of RP in genetic counseling and PND.