SNCA variants rs2736990 and rs356220 as risk factors for Parkinson’s disease but not for amyotrophic lateral sclerosis and multiple system atrophy in a Chinese population

Abstract Previous studies found that polymorphisms rs2736990 and rs356220 in the alpha-synuclein ( SNCA ) gene increase the risk for Parkinson's disease (PD) in a Caucasian population. In consideration of the overlapping of clinical manifestations and pathologic characteristics among PD, amyotrophic lateral sclerosis (ALS), and multiple system atrophy (MSA), the possible associations of these 2 polymorphisms and 3 neurodegenerative diseases were studied in the Chinese population. A total of 1011 PD, 778 sporadic ALS (SALS), 264 MSA patients, and 721 healthy controls (HCs) were studied. All subjects were genotyped for the 2 polymorphisms using polymerase chain reaction and direct sequencing. Significant differences in the genotype frequencies ( p = 0.0188 and 0.0064, respectively) and minor allele frequencies (MAFs) ( p = 0.0065 and 0.0095, respectively) of rs2736990 and rs356220 were observed between the PD patients and HCs. Moreover, significant differences were found between the early-onset PD patients (