Homozygosity Mapping

Abstract

The mapping of genes involved in rare recessive disorders in large outbred population is often a difficult task because of the lack of families with multiple affected individuals. Homozygosity mapping is an efficient gene mapping method applicable to rare recessive disorders in inbred populations. Indeed, the method takes advantage of the fact that inbred affected individuals are likely to have recessive two copies of the disease allele from a common ancestor; i.e. two identical-by-descent alleles. Since small chromosomal regions tend to be transmitted whole, affected individuals will also have identical-by-descent alleles at markers located nearby the disease locus and thus will be homozygous at these markers. The basic idea of the method to locate genes involved in rare recessive traits is thus to search for regions of homozygosity that are shared by different affected individuals

DOCK8 deficiency in six Iranian patients

“…The method takes advantage of the fact that inbred affected individuals are likely to inherit two recessive copies of the disease allele from a common ancestor. Since small chromosomal regions tend to be transmitted as a whole, affected individuals will also have identical‐by‐descent alleles at markers located nearby the disease locus, and thus, will be homozygous at these markers . Homozygosity mapping with microsatellite markers on chromosome 9p was therefore used as diagnostic tool to assess the likelihood of the patients to carry homozygous DOCK8 mutations.…”