The mutation spectrum of Parkinson-disease-related genes in early-onset Parkinson's disease in ethnic Chinese

Abstract

Background and purpose: Recent genetic progress has shown many causative/risk genes linked to Parkinson's disease (PD), mainly in patients of European ancestry. The study aimed to investigate the PD-related genes and determine the mutational spectrum of early-onset PD in ethnic Chinese.

Methods: In this study, whole-exome sequencing and/or gene dosage analysis were performed in 704 early-onset PD (EOPD) patients (onset age ≤45 years) and 1866 controls. Twenty-six PD-related genes and 20 other genes linked to neurodegenerative and lysosome diseases were analysed.

Results: Eighty-two (11.6%, 82/704) EOPD patients carrying rare pathogenic/likely pathogenic variants in PD-related genes were identified. The mutation frequency in autosomal recessive inheritance EOPD (42.9%, 27/63) was much higher than that in autosomal dominant inheritance EOPD (0.9%, 12/110) or sporadic EOPD (8.1%, 43/531). Bi-allelic mutations in PRKN were the most frequent, accounting for 5.1% of EOPD cases. Three common pathogenic variants, p.A53V in SNCA, p.G284R in PRKN and p.P53Afs*38 in CHCHD2, occur exclusively in Asians. The putative damaging variants from GBA, PRKN, DJ1, PLA2G6 and GCH1 contributed to the collective risk for EOPD. Notably, the protein-truncating variants in CHCHD2 were enriched in EOPD, especially for p.P53Afs*38, which was also found in three patients from an independent cohort of patients with late-onset PD (n = 1300). Functional experiments confirmed that truncated CHCHD2 variants cause loss of function and are linked to mitochondrial dysfunction.

Conclusions: Our study reveals that the genetic spectrum of EOPD in Chinese, which may help develop genetic scanning strategies, provided more evidence supporting CHCHD2 in PD.

Keywords: CHCHD2; Parkinson's disease; burden analysis; mutation spectrum.