Objective: To investigate whether α -synuclein levels are altered in serum and saliva in patients with RLS and explore influence of the SNCA-Rep1 microsatellite repeat on restless legs syndrome (RLS).

Background: There is a role of α -synuclein on dopaminergic synaptic transmission and dopamine homeostasis and maybe involved in RLS.

Method: RLS patients were enrolled according to the IRLSSG criteria. A unified semi-structured questionnaire was used to record demographic information and leg restlessness symptoms. Blood and saliva samples were collected to detect α-synuclein protein level and to genotype the SNCA Rep1 marker. Laboratory examinations were performed to exclude secondary RLS.

Results: 71 patients with RLS as well as 56 age and gender matched healthy controls underwent analyses of serum α-synuclein concentration. RLS patients showed decreased serum α-synuclein level compared to age and gender matched controls (10.4±6.2 vs 38.6±9.9ng/ml, p<0.0001). RLS patients without medication demonstrated even lower serum α –syn level than RLS patients with medication (8.8±5.1 vs 14.5±7.1ng/ml, Z=-3.156, P=0.002). Lower serum α-synuclein level was associated with shorter duration of RLS (P<0.05). Levels of α-syn in saliva was similar in RLS patients and controls (P>0.05). 201 RLS patients and 218 healthy controls underwent genotypies. Frequencies of SNCA Rep1 0/0 genotype and allelic 0 variant were significantly lower in RLS patients compared to controls (OR=0.344, 95% CI=0.173-0.684, P=0.002; and OR=0.681, 95% CI=0.512-0.905, P=0.008, respectively). Frequencies of SNCA Rep1 2/2 genotype and allelic 2 were significantly higher (OR=5.186, 95% CI=1.395-19.273, P=0.007; and OR=1.913, 95%CI=1.212-3.021, P=0.005), while Rep1 0/1 genotype and allelic 1 were significantly lower in RLS patients with iron deficiency compared to RLS patients without iron deficiency (OR=0.467, 95%CI=0.239-0.912, P=0.024; and OR=0.649, 95%CI=0.421-0.998, P=0.049). RLS patients with at least one allele 2 showed lower serum α-synuclein level compared to RLS patients without any allele 2 (P<0.05).

Conclusion: Serum α-synuclein level was significantly decreased in patients with RLS and dopaminergic drug therapy may have an impact on level of serum α-synuclein in RLS patients. SNCA Rep1 polymorphism is associated with RLS and its phenotype.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/decreased-serum-alpha-synuclein-in-patients-with-restless-legs-syndrome-and-association-with-snca-rep1-polymorphism/