Epidemiological and genetic insights of Usher syndrome in Turkish population: A cross-sectional preliminary study from University of Health Sciences, Turkey.

ObjectiveThis current cross-sectional study aimed to investigate the demographic characteristics and molecular epidemiology of patients with Usher syndrome in the Turkish population.MethodsPatients who were followed up with a preliminary diagnosis of Usher syndrome from various regions of the country were included in the study. After a review of patients' medical histories, all underwent ophthalmological and otorhinolaryngological examinations. Mutations reported in previous studies in MYO7A, PCDH15, USH1C, CDH23, and USH2A were investigated using Sanger sequencing.ResultsFourteen (29.2%) patients had Usher syndrome type 1 and 16 (33.3%) had type 2. Eighteen (37.5%) patients could not be typed. We detected mutations in MYO7A (c.1343 + 1 G > A) in seven patients (six heterozygous and one homozygous) from seven families clinically compatible with Usher syndrome type 2 (rather than Usher syndrome type 1, as was expected based on previous studies).ConclusionsOur preliminary findings suggest that the proportions of patients with Usher syndrome type 1 and Usher syndrome type 2 in the Turkish population were almost equal, and none of our patients was clinically compatible with Usher syndrome type 3. Although previous studies reported that mutations in MYO7A rarely caused Usher syndrome type 2, in the Turkish population, MYO7A alleles may be hypomorphic and manifest as a milder phenotype in Usher syndrome compared with other populations.