GCH1 and Alzheimer disease: Common variants of the GTP cyclohydrolase 1 (GCH1) gene (rs72713460) and the Potassium inwardly rectifying channel subfamily J member 15 (KCNJ15) gene (rs928771) were first identified as risk factors for AD in the Chinese population since they may affect immune-related pathways, leading to the altered onset age of AD [85].