Sex specific association between carnosinase gene CNDP1 and cardiovascular mortality in patients with type 2 diabetes (ZODIAC-22)

Introduction Homozygosity for a 5-leucine repeat (5L-5L) in the carnosinase gene ( CNDP1 ) has been associated with a reduced prevalence of diabetic nephropathy in cross-sectional studies in patients with type 2 diabetes, particularly in women. Prospective studies on mortality are not available. This study investigated whether 5L-5L was associated with mortality and progression of renal function loss and to what extent this effect is modified by sex. Methods In a prospective cohort of patients with type 2 diabetes, a Cox proportional hazard model was used to compare 5L-5L with other genotypes regarding (cardiovascular) mortality. Renal function slopes were obtained by within-individual linear regression of the estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease (MDRD) equation, and were compared between 5L-5L and other genotypes. Results 871 patients were included (38 % with 5L-5L). After 9.5 years of follow-up, hazards ratios (HR) for all-cause and cardiovascular mortality in 5L-5L versus other genotypes were 1.09 [95 % confidence interval (CI) 0.88–1.36] and 1.12 (95 % CI 0.79–1.58), respectively. There was a significant interaction between CNDP1 and sex for the association with cardiovascular mortality (p = 0.01), not for all-cause mortality (p = 0.32). Adjusted HR in 5L-5L for cardiovascular mortality was 0.69 (95 % CI 0.39–1.23) in men and 1.77 (95 % CI 1.12–2.81) in women. The slopes of eGFR-MDRD did not significantly differ between 5L-5L and other genotypes. Conclusions The association between CNDP1 and cardiovascular mortality was sex-specific, with a higher risk in women with 5L-5L genotype. CNDP1 was not associated with all-cause mortality or change in eGFR.