MITOCHONDRIAL COMPLEX DEFICIENCIES IN A MALE WITH CARDIOMYOPATHY AND 3-METHYLGLUTACONIC ACIDURIA

Excessive excretion of 3-methylglutaconic acid has been associated with a variety of clinical phenotypes (Gibson et al 1991; Chitayat et al 1992), but only in a few cases has the primary metabolic defect been identified. A deficiency of 3-methylglutaryl-CoA hydratase activity is associated with 3-methylglutaric aciduria (MGA) type 1, a relatively mild condition described in only two families. In other patients, such as those with the X-linked cardiomyopathic type (Earth et al 1983; Kelley et al 1991), or the Iraqi-Jewish optic atrophy (Elpeleg et al 1994) or neuropathic (Chitayat et al 1992) types, defects in mitochondrial function have been found (Holme et al 1992; Bakkeren et al 1992; Ibel et al 1993). Recent reports would suggest that excessive excretion of 3-methylglutaconic acid may be a useful marker for underlying respiratory-chain defects. We report such a patient who died with marked cardiomyopathy.