Genetic characteristics of retinitis pigmentosa patients in southeast anatolia

Aim: The aim of this study is to reveal the inheritance pattern and associations of Retinitis Pigmentosa (RP) cases seen in our region using Next Generation Sequencing (NGS) technologies. Material and Methods: Forty patients clinically diagnosed with RP were prospectively evaluated. Patients' histories, uncorrected and corrected visual acuity, intraocular pressure measurements, detailed anterior and posterior segment examinations were performed. Blood samples were taken from the patients in the clinic and sent to the genetic laboratory. The DNA sequence analysis method was applied to the relevant regions from blood samples in the laboratory by using primers containing gene exons with the NGS method. Results: The mean age of the cases was 28,7±15,03, 26 were men and 14 were women. In cases with RP-related gene mutations, 15% (6 patients) autosomal dominant (OD) and 72,5% (29 patients) autosomal recessive (OR) inheritance was detected as genetic inheritance. In 12,5% of the cases (5 patients), no gene mutation could be demonstrated and it was accepted as sporadic/unidentified cases. In our study, 35 patients (87,5%) had non-syndromic RP. While 21 of these (60%) had isolated RP, 14 (40%) of them were accompanied by other ocular syndromes. The most common accompanying ocular pathology was Leber's Congenital Amaurosis. In 12,5% of our patients (5 patients), there were extraocular systemic findings in addition to RP. Usher Syndrome was present in 4 (10%) of these cases, which we consider as syndromic RP. In our cases, mutations were detected in RHO, RP1, BEST1, FSCN2, HMCN1, NR2E3 genes showing OD transition and in ABCA4, NMAT1, USHA2, MYO7A, RDE12, RD3, PDE6A, PDE6B, GNAT1, IQCB1, CYP4V2, MERTK CERKL, PCARE, POMGNT1, PROM 1, RP65, RP1L1 genes showing OR transition. Conclusion: Our study determined that RP in our region showed genetic transmission with the most common OR inheritance pattern. The mutation was mostly seen in ABCA4 and USH2A genes. Usher Syndrome was the most common syndromic form of RP.