A SOD2 Polymorphism is Associated with Abnormal Quantitative Sensory Testing in Type 2 Diabetic Patients

Abstract

Introduction: Diabetes mellitus (DM) affects peripheral nerves inducing diabetic polyneuropathy (DPN). Mitochondria! dysfunction and oxidative stress are potential causes of DPN. Methods: Nerve conduction studies were performed in 20 type 2 DM patients (11 with DPN) and 15 healthy controls. Perception threshold values of cold, warm and vibration were measured by quantitative sensory testing. Variants of a superoxide dismutase 2 (SOD2) gene single nucleotide polymorphism (SNP) (rs5746136) were determined by polymerase chain reaction (PCR) and following NexteraXT DNA Library. Results: DPN patients showed significantly increased threshold values. DM patients without DPN and healthy controls showed comparable values. TT variant of the SOD2 SNP was more prevalent in DM and DPN patients. DM patients with the TT variant displayed increased perception threshold values. Conclusions: Quantitative sensory testing is not superior to standard nerve conduction studies in DPN. Carriers of SOD2 SNP manifested increased sensory threshold levels which is important in further corroborating the link between oxidative stress and DPN.