Approximately 5% of IBD genetic susceptibility factors that have been identified are involved in the regulation of mitochondrial homeostasis, including SLC25A28 encoding mitoferrin 2, PARK7 encoding Parkinson’s disease 7, VARS encoding valine-tRNA ligase, and RNF5 encoding E3 ubiquitin-protein ligase RNF5 (61–63). This evidence concerns the gene VARS1 and Parkinson disease.