The distribution of regions of homozygosity (ROH) among consanguineous populations-implications for a routine genetic counseling service.

Regions of homozygosity (ROH) increase the risk of recessive disorders, and guidelines recommend reporting of excessive ROH in prenatal testing. However, ROH are common in populations that practice endogamy or consanguinity, and cutoffs for reporting ROH in such populations may not be evidence-based. We reviewed prenatal testing results (based on cytogenetic microarrays) from 2191 pregnancies in the Jewish and non-Jewish populations of Northern Israel and estimated the prevalence of ROH according to self-reported ethnicity and parental relationships.