Occurrence of PARK2 Mutations in a Never-Smoker Population with Parkinson’s Disease in North India

Abstract

Background: Parkinson’s disease (PD) is a complex neurological disorder without any well-documented genotype-demography associations among sporadic variants. We recently reported PARK2 mutations to be constituting 40% of PD in this region and thus analysed how demographic variables associate with PARK2 mutations in 70 of these patients. Methods: PD samples were screened by PCR single-strand conformation polymorphism (SSCP) and sequencing and their demographic data collected. Demographic and religion data was obtained from 1,010 randomly selected individuals of 120,000 patients visiting the Neurology Clinic and was compared with state database and PD patients. Results: Sikhs from a rural background exhibited the majority of PARK2 mutations. The frequency of PARK2 mutations among females was significantly higher as compared to males (p < 0.015). The age of onset of PD patients with a rural background was found to be significantly lower as compared to patients with an urban background (p < 0.004). The demographic spectrum of the 1,010 randomly selected patients and the background population was found to be comparable. Conclusions: As PD patients with PARK2 mutations were found to be of sporadic origin and never-smokers, a non-redundant inverse relationship between founder PARK2 mutations and smoking is implicated to account for its high frequency. The predisposition of Sikhs to PARK2 mutations necessitates a larger study among its familial variants and a control smoker PD population. The spectrum of PARK2 mutations among Sikh smokers is difficult to study because of the religion-based aversion to smoking.