Abstract
Olfactory receptors (OR), responsible for detection of odor molecules, belong to the largest family of genes and are highly polymorphic in nature having distinct polymorphisms associated with specific regions around the globe. Since there are no reports on the presence of copy number variations in OR repertoire of Indian population, the present investigation in 43 Indians along with 270 HapMap and 31 Tibetan samples was undertaken to study genome variability and evolution. Analysis was performed using Affymetrix Genome-Wide Human SNP Array 6.0 chip, Affymterix CytoScan® High-Density array, HD-CNV, and MAFFT program. We observed a total of 1527 OR genes in 503 CNV events from 81.3% of the study group, which includes 67.6% duplications and 32.4% deletions encompassing more of genes than pseudogenes. We report human genotypic variation in functional OR repertoire size across populations and it was found that the combinatorial effect of both “orthologous obtained from closely related species” and “paralogous derived sequences” provide the complexity to the continuously occurring OR CNVs.
Highlights
Olfactory receptors (OR) belong to the hyperfamily of sevenhelix G-protein-coupled receptors (GPCRs), involved in conversion of the odorant into odor sensation [1]
43 normal members from randomly selected twelve families residing in Karnataka, India, with different age group members ranging from 13–73 years, 270 HapMap samples covering CEU (CEPH collection), CHB (Han Chinese in Beijing, China), JPT (Japanese in Tokyo, Japan) and YRI (Yoruba in Ibadan, Nigeria) populations and 31 Tibetan samples were selected for copy number polymorphism analysis of the OR subgenome. 5 ml EDTA blood was collected from each member of the Indian study group and genomic DNA was extracted using
Multigene families comprise of genes that are identical or having similar sequence and the similarity can be either for the entire sequence or partial, limited to specific domains
Summary
Olfactory receptors (OR) belong to the hyperfamily of sevenhelix G-protein-coupled receptors (GPCRs), involved in conversion of the odorant into odor sensation [1] This sense of smell includes a cascade of biochemical and electrophysiological processes to detect and discriminate millions of odorous compounds [2]. These olfactory receptors constitute the largest mammalian multi-gene family organized in 40 clusters across 21 chromosomes [3]. Such a cluster organization is the result of extensive processes of expansion, diversification, duplication, deletion and pseudogenization [4]. OR copy number polymorphisms (CNPs) have been reported in samples covering Africans, Middle
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