No correlations between contactin-1 and -2 levels and clinical measures of PD severity, i.e., H&Y scale (r = 0.002, p = 0.98) and UPDRS-III (r = 0.16, p = 0.39) and disease duration (r = −0.01, p = 0.93) were observed. This evidence concerns the gene CNTN1 and Parkinson disease.