[PREVALENCE OF ASTIGMATISM BEFORE ROUTINE CATARACT SURGERY: COMPARISON BETWEEN BEDOUIN AND JEWISH POPULATION IN SOUTHERN ISRAEL].

OBJECTIVES: To assess the prevalence of corneal astigmatism among patients before routine cataract surgery and overall ocular difference between Jewish and Bedouin population in the south of Israel. METHODS: Retrospective research collecting biometric information from IOLMaster (Carl Zeiss Meditec AG, Germany) in patients attending cataract surgery at Soroka University Medical Center, Beer-Sheva, Israel between the years 2015 -2016. RESULTS: Mean corneal astigmatism among all cohorts was 1.20D ± 0.83, with 1.26D ± 0.84 in Bedouins patients vs 1.17D ± 0.82 in Jews patients (p-value=0.08). Corneal astigmatism lower than 0.5D was seen in 20% of the population, 28% of the population had corneal astigmatism above 1.5D and 9% showed corneal astigmatism higher than 2.5D. When comparing axial length and keratometric characteristics between the two populations, Bedouins had shorter axial length (23.41mm± 1.62 vs. 23.67mm ± 1.55, p=0.01), and flatter corneas on both axes (flat - 43.18D ± 1.76 vs. 43.62D ± 1.79, p<0.01); (steep - 44.44D ± 1.84 vs. 44.77D± 1.89, p<0.01). Higher astigmatism was found in men than in women (1.24D vs.1.15D p- value=0.04) of study group. CONCLUSIONS: In our study we found more than 25% of patients had astigmatism more than 1.5D. Patients attending cataract surgery may therefore benefit the use of advanced IOL types and surgical techniques. In addition, a statistically significant difference between the Bedouin and Jewish populations biometric measurements in patients attending cataract surgery found.

Combined CNV, haplotyping and whole exome sequencing enable identification of two distinct novel EYS mutations causing RP in a single inbred tribe.

Whole exome sequencing (WES) has become routine in clinical practice, especially in studies of recessive hereditary diseases in inbred consanguineous families, where homozygosity of a founder mutation is assumed. Multiple members of two consanguineous families of a single Bedouin tribe were diagnosed with apparently autosomal recessive/pseudo-dominant retinitis pigmentosa (RP). Affected individuals exhibited severe visual impairment with nyctalopia, marked constriction of visual fields, markedly reduced and delayed responses on electro-retinography (ERG) and eventual loss of central vision. Combined copy-number variant (CNV) analysis, haplotype reconstruction and WES of the kindred identified two distinct novel mutations in EYS (RP25): a p.(W1817*) nonsense mutation (identified through WES) and a large deletion encompassing 9 of the 43 exons, that was missed by WES and was identified through microarray CNV analysis. Segregation analysis of both mutations demonstrated that all affected individuals were either homozygous for one of the mutations, or compound heterozygous for both. The two mutations are predicted to cause loss of function of the encoded protein and were not present in screening of 200 ethnically-matched controls. Our findings of two distinct mutations in the same gene in a single inbred kindred, identified only through combined WES and microarray CNV analysis, highlight the limitations of either CNV or WES alone, as the heterozygous deletion had normal WES read-depth values. Moreover, they demonstrate pitfalls in homozygosity mapping for disease-causing variant identification in inbred communities.