FMR1 and fragile X syndrome: Besides being a PD GWAS gene, PAK1 may also modulate or bind with other disease proteins, including Fragile X mental retardation 1 (FMR1) for Fragile X syndrome (FXS), the most commonly inherited form of mental retardation and autism [140]; Disrupted-in-Schizophrenia 1 (DISC1) for schizophrenia [141]; ALS2/Alsin for amyotrophic lateral sclerosis (ALS) [142], and Down syndrome cell adhesion molecule (DSCAM) [143].