A common variant of the p16(INK4a) genetic region is associated with physical function in older people

Abstract

p16(INK4a) is active in cell senescence, ageing and tumor suppression. Deletion of the small p16(INK4a)/ARF/p15(INK4b) region occurs in many cancers. We screened 25 common polymorphisms across the region and three related genes for associations with physical functioning in older people. In an initial sample of 938 (aged 65-80 years) from the EPIC study (Norfolk, UK), the rs2811712 SNP minor allele (located between the shared p16(INK4a)/ARF locus and p15(INK4b)) was associated with reduced physical impairment. This association remained after testing an additional 1319 EPIC-Norfolk samples (p-value=0.013, total n=2257), and on independent replication in the InCHIANTI study (n=709, p=0.015), and at one-sided significance in Iowa-EPESE (n=419, p=0.079). Overall (n=3372), the prevalence of severely limited physical function was 15.0% in common homozygotes and 7.0% in rare homozygotes (per minor allele odds ratio=1.48, 95% CI: 1.17-1.88, p=0.001, adjusted for age, sex and study). This estimate was similar excluding screening set 1 (OR=1.45, 95% CI: 1.09-1.92, p=0.010, n=2434). These findings require further replication, but provide the first direct evidence that the p16(INK4a)/ARF/p15(INK4b) genetic region and the senescence machinery are active in physical ageing in heterogeneous human populations. The mechanism involved may be via greater cellular restorative activity and reduced stem cell senescence.

Fig. 1

Percentage with severely limited physical function by rs2811712 genotype, all studies combined (participants aged 65 to 80 years, per minor allele adjusted logistic regression p=0.001)* Note: * age, sex and set/study adjusted, logistic regression model based estimates