Abstract
Purpose:
To determine the prevalence of nonsyndromic retinitis pigmentosa (RP) in the Jerusalem region with a population size of about one million individuals.
Methods:
Medical records of patients with retinal diseases were collected over the last 20 years and included mainly clinical eye exam findings (visual acuity, anterior segment and funduscopy) and electroretinography (ERG). Data was collected on patients who were diagnosed with RP and reside in the vicinity of Jerusalem. Mutation analysis on a subgroup of patients was performed by the candidate gene analysis, homozygosity mapping and whole exome sequencing.
Results:
A total of 435 individuals who reside in the vicinity of Jerusalem were diagnosed with RP at our center, according to funduscopic findings and ERG testing. Based on the estimated population size of 945,000 individuals who reside in the vicinity of Jerusalem, the non-corrected estimated prevalence of nonsyndromic RP is 1:2,172. There are two main subpopulations in this area: Jews (65% of the population) and Arab-Muslims (35%). The prevalence of RP was found to be higher among Arab Muslims (1:1,848) compared to Jews (1:2,326), mainly due to consanguineous marriages. To identify the genetic causes of RP in our cohort, we recruited 243 of the patients who belong to 167 families: 61 with autosomal recessive (AR) inheritance, 13 autosomal dominant, 29 isolate cases with consanguinity (indicative of AR inheritance pattern), 51 nonconsanguineous isolate cases, and 13 with X-linked inheritance pattern. In 52 (31%) of the families, we identified the genetic cause of disease, allowing us to revise the inheritance pattern of 13 nonconsanguineous isolate cases to AR pattern, which comprise 44% of families. Interestingly, in 29 (58%) of the solved families, the cause of disease was a founder mutation, identified in the following genes: CRB1, DHDDS, EYS, FAM161A, NR2E3, and RPGR.
Conclusions:
Previous studies showed a prevalence of 1:5,663 (on average) for nonsyndromic RP at all ages in the American and European populations. We show here that the prevalence in the vicinity of Jerusalem is 2.5 times higher than the prevalence reported previously in Maine and Denmark. This high prevalence is likely to be due to a high level of consanguinity in the studied population in association with highly prevalent founder mutations.
Keywords: 463 clinical (human) or epidemiologic studies: prevalence/incidence •
539 genetics •
696 retinal degenerations: hereditary