SLC39A8 and Parkinson disease: Genome-wide association studies (GWAS) have indicated that a specific variant of the zinc transporter ZIP8 is significantly linked to the risk of schizophrenia and Parkinson’s disease (PD).219 Severe homozygous loss-of-function mutations in ZIP8 lead to a type-II congenital disorder of glycosylation, increasing the risk of schizophrenia.93,220 Furthermore, ZIP8 hypofunction may contribute to psychiatric risk by causing glutamate receptor hypofunction and heightened inflammation.