It was hypothesized that CNVs play an important role in the evolution of the human olfactory repertoire (29). About half of the CNVs affecting the human OLR repertoire involve more than one OLR. It was also observed that CNVs were more frequent among pseudogenes of OLRs than among functional genes (29). Comparison to the chimpanzee, reference genome revealed that all of the detected deletion alleles are human derived. This indicated a profound effect of human-specific deletions on the individual OLR gene content. It was suggested that these deletion alleles may be used in future genetic association studies of olfactory inter-individual differences (29). Evidence was provided for OLR enrichment in CNVs not being due to positive selection but due to the dominance of OLR in segmentally duplicated regions (30). Additionally, purifying selection against CNVs is lower in regions containing OLRs than in regions containing essential genes (30). A possible link between OLRs and obesity has previously been suggested based on the observation of altered olfactory acuity in morbidly obese patients (31).
