De novo mutation in ancestral generations evolves haplotypes contributing to disease

We investigated the influences of admixture and consanguinity on the genetic architecture of disease by generating a database of variants derived from exome sequencing (ES) of 853 unrelated Turkish (TK) individuals with different disease phenotypes. We observed that TK genomes are more similar to Europeans with 69.3% of the unique variants (N = 356,613) not present in the Greater Middle Eastern variome. We found higher inbreeding coefficient values in the TK cohort correlating with a larger median span of long-sized (>1.606 Mb) runs of homozygosity (ROH). We show that long-sized ROHs arose from recently configured haplotypes and are enriched for rare homozygous deleterious variants. Such haplotypes, and the combinatorial effect of their embedded ultra-rare variants, provide the most explanatory molecular diagnoses for the TK individuals observed disease traits. Such haplotype evolution results in homozygosity of disease associated haplotypes due to identity-by-descent in a family or extended clan.