Therefore, in this study we will devote to explore: (1) to compare whether the proportion of T-cell subsets and the levels of serum immunoglobulins IgG, IgM, and IgA in MSA patients and normal controls are different, and (2) to test whether the PIA state of MSA patients would correlate with the disease subtype as well as to analyze the role of PIA in the progression of the disease. This evidence concerns the gene CD40LG and multiple system atrophy.