We examined 41 skin biopsies from genetic PD patients (CHCHD2, n = 4; RAB39B, n = 2; GBA, n = 5; PRKN, n = 16; and LRRK2, n = 14) and retrieved 64 skin biopsy and 205 brain autopsy genetic PD patients from the literature review (Table 4). The gene discussed is GBA1; the disease is Parkinson disease.