First RR-MADD mouse model with an Etfdh (h)p.84A > T mutation.The mice, initially normal, developed the clinical and biochemical features typical of MADD under high fat and Rf deficiency diet. Tissues from these mice exhibited a significant decrease of both FAD concentration and ETFDH protein level, which were ameliorated by Rf treatment. The gene discussed is ETFDH; the disease is multiple acyl-CoA dehydrogenase deficiency.