A dinucleotide repeat polymorphism at the poly(ADP-ribose) polymerase gene is not associated with predisposition to type 1 diabetes in French Caucasians

The poly (ADP-ribose) polymerase (PARP) is a nuclear enzyme that detects and binds DNA strand breaks. Excessive PARP activation leads to the death of mice islet beta-cells by depleting cellular energy reserves. On the other hand, PARP-mutant mice are resistant to streptozotocine-induced diabetes, and in the non-obese diabetic (NOD) mouse model, treatment with nicotinamide, a PARP inhibitor, protects islet cells against cytotoxic actions in vitro and results in a decreased incidence of type 1 diabetes. PARP gene in human is located within a recently identified type 1 diabetes-susceptibility region on chromosome 1q41-42, and contains a polymorphic CA dinucleotide repeat in the promoter region. To consider the putative involvement of PARP polymorphism in predisposition to type 1 diabetes, we performed genotyping for the various alleles of the CA dinucleotide repeat in 158 unrelated French Caucasian patients with type 1 diabetes and 193 ethnically-matched healthy controls. We found no significant difference of PARP alleles distribution between patients and controls, even after stratification of the patients according to HLA class II genotype or to age at disease onset. Our results suggest that this PARP polymorphism does not influence susceptibility to type 1 diabetes in French Caucasians.