A Complex FGF14 (TTC)/(TGC) Repeat Expansion in Parkinson's Disease

Area of Science:

• Genetics
• Neuroscience
• Molecular Biology

Background:

• Repeat expansions are known genetic risk factors for Parkinson's disease (PD).
• The FGF14-SCA27B (GAA)•(TTC) repeat locus, a novel repeat expansion site, remained unexplored in PD research.
• Investigating novel genetic loci is crucial for understanding PD etiology.

Purpose of the Study:

• To investigate the role of FGF14 repeat expansions as a potential genetic risk factor for Parkinson's disease (PD) in the Asian population.
• To characterize the sequence composition and genotypic patterns of FGF14 repeat expansions.
• To determine the association between FGF14 repeat expansions and PD risk through case-control studies.

Main Methods:

• Genetic sequencing and polymerase chain reaction (PCR) techniques were employed to detect pure and complex repeat expansions in the FGF14 gene in Asian PD patients.
• Targeted long-read sequencing was utilized to analyze the detailed sequence composition of identified repeat expansions.
• Case-control studies were conducted to assess the association between FGF14 repeat expansions and PD risk.

Main Results:

• A pure (TTC)≥250 repeat expansion was found in 0.17% of PD patients.
• A complex (TTC)/(TGC)≥300 repeat expansion, with four distinct segments and genotypic patterns, was identified as the main expanded genotype.
• Pattern 4 of the complex (TTC)/(TGC) repeat expansion showed significant enrichment in PD patients compared to controls, confirmed across discovery, replication, and meta-analysis cohorts (P=0.015, OR=1.75).

Conclusions:

• A unique complex (TTC)/(TGC) repeat expansion in the FGF14 gene represents a novel genetic risk factor for Parkinson's disease (PD) in the Asian population.
• This discovery expands the known genetic landscape of PD and implicates FGF14 in its pathogenesis.
• Further research into FGF14 repeat expansions may offer new diagnostic and therapeutic avenues for PD.