Other genes in the region, such as hyperpolarization-activated cyclic nucleotide-gated potassium channel 2 (HCN2), mucosal vascular addressin cell adhesion molecule 1 (MADCAM1), and fibroblast growth factor 22 (FGF22) genes, may also have an etiologic link to MSA, because they exert their functions in the nervous system. Here, MADCAM1 is linked to multiple system atrophy.