Deficiency of ETF-QO results in a disorder known as glutaric acidemia type II (also known as MADD for multiple acyl-CoA dehydrogenase deficiency), in which there is an improper buildup of fats and proteins in the body. Complications can involve acidosis or hypoglycemia, with other symptoms such as general weakness, liver enlargement, increased heart failure, and carnitine deficiency. More severe cases involve congenital defects and full metabolic crisis. Genetically, it is an autosomal recessive disorder, making its occurrence fairly rare. Most affected patients are the result of single point mutations around the FAD ubiquinone interface. Milder forms of the disorder have been responsive to riboflavin therapy and are coined riboflavin-responsive MADD (RR-MADD), although due to the varying mutations causing the disease treatment and symptoms can vary considerably.