Objective: We sought to investigate the relationship between SNCA Rep1 allele length and NMS in PD.

Background: Associations between the alpha-synuclein gene (SNCA) promoter region (Rep1) polymorphism (long- vs short-allele carriers) and Parkinson’s’ disease (PD) is well-established, with longer Rep1 allele carriers displaying increased risk of developing PD and greater motor decline in multiple studies than short allele carriers. Non-motor symptoms (NMS) are important features at early stages of PD and has a major impact on quality of life of PD patients. To date, there are limited studies that investigate the association of Rep1 genotype with PD NMS.

Method: A total of 133 patients with early PD (disease duration £ 1 year) were included in this study. Patients were genotyped and grouped according to Rep1 allele length: ‘1’ and ‘2’ coding as “short”, while ‘3’ coding as “long” in line with previous studies. Non-motor symptoms, such as sleep impairment, fatigue, mood disturbance, perceptual problems, gastrointestinal tract problems etc, were assessed by the Non-Motor Symptom Scale (NMSS); Anxiety and depression were assessed by Hospital Anxiety and Depression Scale (HADS). Higher scores in these scales represent more severe symptoms.

Results: PD patients were stratified into short (n=60) and long (n=72) carriers. There were no significant differences in age, gender, and disease duration according to Rep1 allele length in PD patients. By comparing NMSS scores, patients with longer Rep1 alelles had overall more severe NMSS total score (p=0.016), comparing to patients with shorter Rep1 alleles. HADS depression scores were significantly higher in patients with longer Rep1 alleles (p=0.002), but not HADS anxiety scores (p=0.921), comparing to patients with shorter alleles. These results remained significant in multivariate comparisons that controlled for age, gender and disease duration.

Conclusion: Our findings suggest that SNCA Rep1 allele length influences non-motor aspects in early PD, with patients carrying longer Rep1 alleles showing worse NMS and depression scores. Future research in larger cohort are needed to confirm these findings, which will help to identify subsets of patients at risk of NMS, especially in early pre-symptomatic stage.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/alpha-synuclein-promoter-snca-rep1-polymorphism-is-associated-with-non-motor-symptoms-in-early-parkinsons-disease/