Genome-wide association study identifies variants in casein kinase II (CSNK2A2) to be associated with leukocyte telomere length in a Punjabi Sikh diabetic cohort.

Background-Telomere length is a heritable trait, and short telomere length has been associated with multiple chronic diseases. We investigated the relationship of relative leukocyte telomere length with cardiometabolic risk and performed the first genome-wide association study and meta-analysis to identify variants influencing relative telomere length in a population of Sikhs from South Asia. Methods and Results-Our results revealed a significant independent association of shorter relative telomere length with type 2 diabetes mellitus and heart disease. Our discovery genome-wide association study (n=1616) was followed by stage 1 replication of 25 top signals (P<10(-6)) in an additional Sikhs (n=2397). On combined discovery and stage 1 metaanalysis (n=4013), we identified a novel relative telomere length locus at chromosome 16q21 represented by an intronic variant (rs74019828) in the CSNK2A2 gene (beta=-0.38; P=4.5x10(-8)). We further tested 3 top variants by genotyping in UK cardiovascular disease (UKCVD) (whites n=2952) for stage 2. Next, we performed in silico replication of 139 top signals (P<10(-5)) in UK Twin, Nurses Heart Study, Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, and MD Anderson Cancer Controls (n=10033) and joint meta-analysis (n=16998). The observed signal in CSNK2A2 was confined to South Asians and could not be replicated in whites because of significant difference in allele frequencies (P<0.001). CSNK2A2 phosphorylates telomeric repeat binding factor 1 and plays an important role for regulation of telomere length homoeostasis. Conclusions-By identification of a novel signal in telomere pathway genes, our study provides new molecular insight into the underlying mechanism that may regulate telomere length and its association with human aging and cardiometabolic pathophysiology.