Parkinson's Disease in Colombia: Do mutations in LRRK2 play a role?

Genetic variation in the leucine-rich repeat kinase 2 (LRRK2) gene (G2019S, R1441C, R1441G) represents the most common determinant of Parkinson’s disease to date. While the distribution of LRRK2 mutations have been well-studied in Asia, Europe, and North America, there is little data available from South America and no data whatsoever in Colombia. Our study consisted of a total 203 patients with PD (102 females, 101 males). The mean age was 66.2 years old and the mean age at onset 51.3 years old. Samples were collected from the University of Antioquia in Medellin, Colombia. We sought to assess the frequency of the most common pathogenic LRRK2 substitutions in patients from Colombia. DNA was extracted from the peripheral blood leukocytes using standard extraction techniques. We then diluted and plated all our samples to a concentration of 5ng/ul to be used for genotyping. Codon 1441 substitutions were genotyped by PCR followed by sequencing of the LRRK2 exon 31 using the Applied Biosystems Big-Dye. Terminator v3.1 Cycle Sequencing Kit. Agarose gels were used to determine PCR success. G2019S was genotyped by Taqman Assay on an ABI 7900HT Sequence Detection System. Positive controls for all three genotypes which were confirmed by sequencing were included in all genotyping runs. All identified carriers were also confirmed using sequencing of LRRK2 exon 41 using the same methods explained above. Out of the 203 patient samples tested 3 samples (1.4%) were positive for the G2019S mutation.