Analysis of LRRK2, SNCA, Parkin, PINK1, and DJ-1 in Zambian patients with Parkinson's disease

Recent studies delineate substantial genetic components in Parkinson's disease (PD). However, very few studies were performed in Sub-Saharan African populations. Here, we explore the contribution of known PD-causing genes in patients of indigenous Zambian ancestry. We studied thirty-nine Zambian patients, thirty-eight with PD and one with parkinsonian-pyramidal syndrome (18% familial; average onset age 54.9 ± 12.2 years). In the whole group, all SNCA exons and LRRK2 exons 29 to 48 (encoding for important functional domains) were sequenced. In the familial patients and those with onset <55 years (n = 22) the whole LRRK2 coding region was sequenced (51 exons). In the patients with onset <50 years (n = 12), all parkin, PINK1, and DJ-1 exons were sequenced, and dosage analysis of parkin, PINK1, DJ-1, LRRK2, and SNCA was performed. Dosage analysis was also performed in the majority of the late-onset patients. The LRRK2 p.Gly2019Ser mutation was not detected. A novel LRRK2 missense variant (p.Ala1464Gly) of possible pathogenic role was found in one case. Two heterozygous, likely disease-causing deletions of parkin (exon 2 and exon 4) were detected in an early-onset case. Pathogenic mutations were not detected in SNCA, PINK1, or DJ-1. We also report variability at several single nucleotide polymorphisms in the above-mentioned genes. This is the first molecular genetic study in Zambian PD patients, and the first comprehensive analysis of the LRRK2 and SNCA genes in a Sub-Saharan population. Common disease-causing mutations were not detected, suggesting that further investigations in PD patients from these populations might unravel the role of additional, still unknown genes.