ADH4 and Parkinson disease: Currently, there is a paucity of research linking the major PD clinical entities of idiopathic PD and familial PD to AUD, and the major association of PD with alcoholism stems from the fact that some alleles of the ADH1 and ADH4 genes—for which there is a truncating G78 stop mutation (allele rs283413) and a functionally impaired allele comprising two linked SNPs (rs34925826 and rs11480228)—are associated with PD [49,50].