ACOX3 and familial dilated cardiomyopathy: Besides, HADHA and HADHB, genes coding for key enzymes in mitochondrial FAO (76), showed generally suppressed mRNA levels in DCM and HCM, whereas ACOX1, ACOX2, and ACOX3, genes coding for key enzymes in peroxisomal FAO (77), showed increased mRNA levels in DCM but not in HCM.