Evidence for depletion of CASP5 Ala90Thr heterozygous genotype in aged subjects

Our previous studies, which included genotyping of multiple coding apoptotic gene polymorphisms, unexpectedly demonstrated a depletion of heterozygous CASP5 Ala90Thr (rs507879, c.268 G > A) genotypes in elderly subjects. Present investigation was aimed to validate this trend. An analysis of 510 subjects aged 75–103 years revealed 205 (40%) CASP5 Ala90Thr heterozygotes as compared to 254 (50%) expected from the minor allele frequency 0.470 (p = 0.000014). This deviation was not observed in 549 middle-aged (18–50 years) controls (270 (49%) heterozygotes observed vs. 274 (50%) expected; minor allele frequency 0.475; p = 0.743). Unfavorable significance of CASP5 heterozygous genotype may be explained by the role of the caspase-5 in inflammation-related processes. Almost all prior gene-longevity association studies focused on discrimination between “good” and “bad” gene variants. Here we present a distinct situation, where the combination of alternative alleles (i.e., heterozygosity) appears to be unfavorable as compared to the homozygous carriership of either gene variant.