Reduced serum progranulin level might be associated with Parkinson's disease risk

Background and purpose Common genetic variants (rs5848 and rs646776) have been reported as regulators of blood progranulin (GRN) levels in healthy individuals. Methods To assess the influence of rs5848 and rs646776 polymorphisms in both serum GRN level and risk for common neurodegenerative diseases, we studied 304 patients with Parkinson's disease (PD), 217 individuals with Alzheimer's disease, 131 subjects with mild cognitive impairment, and 126 controls. Results The mean concentration of GRN in the serum of patients with PD (319.6 ng/ml) was significantly lower than that of controls (371.5 ng/ml; P = 0.009), whereas there were no significant differences between other groups. Rs646776 minor allele carriers had lower serum GRN levels in each of the four subgroups. There was no correlation between rs5848 genotypes and serum GRN concentrations. Genotype frequencies of both polymorphisms did not differ between groups. Conclusion Reduced circulating GRN levels might be associated with PD risk by pathogenic factors different from rs5848 and rs646776 polymorphisms.