Widespread Divergence of the CEACAM/PSG Genes in Vertebrates and Humans Suggests Sensitivity to Selection

Chang, Chia Lin; Semyonov, Jenia; Cheng, Po Jen; Huang, Shang Yu; Park, Jae Il; Tsai, Huai-Jen; Lin, Cheng-Yung; Grützner, Frank; Soong, Yung Kuei; Cai, James J.; Hsu, Sheau Yu Teddy

Third, genetic variations at the CEACAM/PSG locus could be associated with functional elements that were selected by the environment. Recent analyses of SNPs showed that human genomes contain hundreds of loci that exhibit signatures of positive selection (i.e., gene-environmental interactions) [56, 76] , and a number of these genetic variants are associated with the evolution of a variety of common traits (e.g., appearance, physiological adaptations) and pathologies in humans [76, 77, 78, 79] . Likewise, CNVs have been associated with a number of human phenotypes and diseases [80, 81] . For example, amylase CNVs were highly associated starch contents of the food among human populations [82] , whereas, CNVs at the CCL3L-CCL4L locus were associated with the susceptibility to autoimmune disorders, HIV-1 infection, and asthma [83, 84, 85] . While PSG physiology could be dosage insensitive (PSG copy number could range from 12 to 30 in normal individuals), the observation that CEACAM/PSG variations are comparable to those of genes under rapid adaptive evolution in primates [86, 87] suggested that CEACAM/PSG variation-associated changes in functional characteristics or gene expression could help determine survival and reproductive success of the carrier.