Genetic Screening of Colombian Patients With Early-Onset Parkinson Disease

Early-onset Parkinson disease (EOPD), defined as symptom onset before 50 years of age, accounts for approximately 10% of patients and is suggested to have a greater genetic component than typical late-onset forms of the disease. Recessive variants in PRKN, PINK1, and DJ-1, are the most common genetic cause of EOPD, however, most studies are in patients of white ancestry. This study aims to analyze genetic variants in PRKN, PINK1, and DJ-1 in Colombian patients to help address the gap in EOPD genetic research of South American populations.

We analyzed 43 unrelated patients with EOPD using Sanger sequencing for the PRKN, PINK1, and DJ-1 genes and employed multiplex ligation-dependent probe amplification to detect copy number variants. Additionally, long-read whole-genome sequencing was conducted on 3 unresolved patients with age at onset before 30 years of age (long-read sequencing [LRS] patient A-C).

We identified known pathogenic single-nucleotide variants and copy number variants in the PRKN gene accounting for 2 patients' disease (4.6% of patients). We observed 2 pathogenic variants in PRKN (c.155delA; p.N52Mfs*29 and c.1083+1G>A) in patient 1, who reported an age at onset of 16 years. We further detected a homozygous duplication of PRKN exons 5-6 in an additional patient, age at onset of 18 years.

Our study helps characterize genetic contributors to EOPD in Colombian patients, demonstrating genetic forms (PRKN, PINK1, and DJ-1) are rare. Our results highlight a need to include diverse populations in research to improve genetic understanding of disease.