PARK2 and PARK7 Gene Polymorphisms as Risk Factors Associated with Serum Element Concentrations and Clinical Symptoms of Parkinson's Disease.

Besides clinical and imaging techniques, there is a lack of molecular makers for the diagnosis of Parkinson's disease (PD). There is an immense need to develop biomarkers associated with the phenotypes which may be valuable for individualized treatment. Single-nucleotide polymorphisms (PARK2: Ser167Asn (G>A) and Val380Leu (G>C); PARK7: IVS4 + 46G>A and IVS4 + 30T>G) in PD-related genes were examined to elucidate its relationship with concentration of serum elements and clinical symptoms of PD. A total of 214 PD patients and 213 controls from Indian population were genotyped using PCR and DNA sequencing methods. The serum element concentrations were detected and clinical symptoms were determined based on UPDRS scale and recorded at the time of sample collection. The IVS4 + 30T>G, Ser167Asn (G>A) and Val380Leu (G>C) polymorphisms appeared to alter element concentrations in PD. The patients with Ser167Asn polymorphism showed significant association with copper, iron and zinc that reinforces the role of A allele as a factor for change in the concentrations of elements, than those patients with G allele. In particular, patients with A allele of Ser167Asn have risk of having high serum iron concentration (OR 11.55, 95% CI 5.59-23.85), which are associated with dementia and postural imbalance. Similar results were observed for Val380Leu (G>C) and IVS4 + 30T>G polymorphisms which suggest their role in element concentration and neurological symptoms. Overall, our study demonstrates the influence of polymorphisms of PD genes on element concentrations and clinical symptoms. Results of this study may be taken into account when considering the contributing factors for PD symptoms.