What does a region of homozygosity (ROH) typically suggest?

A region of homozygosity (ROH) typically indicates an increased risk of genetic disorders due to consanguinity. When individuals are related, such as parent and child, or siblings, there is a higher chance that they will carry the same alleles at certain loci. As a result, offspring may receive the same allele from both parents, leading to a homozygous state for those regions of the genome.

This phenomenon can be particularly significant in populations where consanguineous marriages are common, as it may lead to a higher prevalence of autosomal recessive disorders. These disorders require two copies of a defective gene for the phenotype to be expressed, so if both parents are carriers of the same recessive mutation, their offspring have an increased risk of being affected if they inherit both copies of the mutation.

In contrast, the other options do not accurately reflect what a ROH indicates. Non-syndromic developmental delay may occur for various reasons, but it is not specifically linked to homozygosity. The presence of balanced rearrangements would generally involve structural variations in chromosomes that do not necessarily relate to homozygosity. Lastly, a complete absence of SNPs is not characteristic of ROH, as ROH can actually encompass regions