COXFA4 and diabetes mellitus: The current in-depth exploration of Ndufa4 as a mitochondrial functional candidate gene involved in the pathogenesis of diet-induced diabetes was driven by our previous localization of the gene by linkage analysis to a diabetes-related quantitative trait locus (QTL) on rat chromosome 4 (RNO4), and the differential expression of the gene between the diabetes-prone CDs/y and -resistant CDr/y strains (Barkalifa et al., 2010; Yagil et al., 2007, 2016).