TMEM175 and Parkinson disease: To assess the genetic contribution of TMEM175 gene in the Italian population, we performed a retrospective observational monocentric study of 400 PD patients (178 familiar and 222 sporadic cases; mean age at diagnosis 58.26 years (standard deviation (SD) 9.74)) [8, 20] and 300 unrelated healthy subjects (mean age 77 years; SD 5.4).