Next generation sequencing using molecular inversion probes in hereditary retinal disorders genes in Polish patients: an update

Abstract

Purpose : The knowledge of mutational spectrum in hereditary retinal disorders (HRDs) within Polish population is still limited. Our ongoing project targets known HRD genes in Polish families with Stargardt’s disease, retinitis pigmentosa, choroideremia, cone- and cone-rod dystrophy, achromatopsia and congenital stationary night blindness. The purpose is to gain knowledge about the type and prevalence of causative variants. Hitherto, we provide an update on this research.

Methods : We collected DNA samples from 208 Polish families suffering from HRD. One family withdrew from the project. Thus far, 162 probands underwent next generation sequencing. A molecular inversion probes pool was used, which targeted 108 HRD genes known in 2013. Subsequently, we analyzed the samples with the use of SeqNext module of SeqPilot software. We then applied filtering for known variants occurring with frequency >0,5% in public databases, with the exception of ABCA4 mutations, when the frequency filter was set to 3%. In case of novel missense or splicing mutations, we applied in-silico prediction software to assess mutation causality.

Results : We detected potentially causative mutations in116 of the 162 HRD families (71%); 60 individuals with STGD, RP and CD/CRD carried ABCA4 mutations (4 single-allelic). On top of previously reported 9 novel mutations from this study, additional novel variants were found in ABCA4, RHO, MAK and CNGA3. The complex allele [c.1622T>C,c.3113C>T] [p.Leu541Pro,p.Ala1038Val] was found in 33 individuals suffering from ABCA4-related disorders, which makes it the most prevalent allele in Polish population (55%). In one case, after genetic screening, the diagnosis changed from RP to choroideremia, which may have impact on future gene therapy in this family.

Conclusions : Our results indicate that ABCA4 mutations are the most common cause of HRDs in Poland. Therefore, it should be the first gene to be analysed. Additionally, it needs to be stressed that in some cases genetic analysis of the patient is necessary to achieve accurate diagnosis.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.