A rare cause of episodic vomiting: Late-onset multiple acyl-CoA dehydrogenase deficiency as a treatable metabolic myopathy

Introduction: Multiple acyl-CoA dehydrogenase deficiency is a rare inherited metabolic disorder of fatty acid, amino acid, and choline metabolism, caused by recessive mutations in the ETFA, ETFB, and ETFDH genes. Herein, we present a case of late-onset MADD, who presented with neck weakness and episodes of vomiting. Case presentation: An 11-year-old boy presented with vomiting attacks, easy fatigue, and weight loss for the last 6 months. He was referred to our hospital for further investigation with a suspicion of a possible malignancy. Prenatal, natal, and developmental history was normal. Family history revealed parental consanguinity and a deceased sibling at the age of 3 years following a febrile infection. On neurological examination, he had prominent cervical and proximal weakness, nasal speech, dysphagia, and absent deep tendon reflexes. Laboratory workup showed elevated transaminase (AST/ALT: 1645/895 U/L) and serum creatinine kinase levels (2389 U/L). Metabolic tests showed characteristic acylcarnitine profile suggestive of MADD deficiency. Molecular analysis of the ETFDH gene confirmed a homozygous pathogenic variant c.1130T>C (p.Leu377Pro). He showed dramatic improvement to high-dose riboflavine, coenzyme Q 10, and carnitine supplementations. On sixth month follow-up, he had normal systemic and neurological examination without any symptoms. Conclusion: Since it is a treatable disorder, the diagnosis of MADD deficiency should be considered especially in patients presenting with fluctuating proximal/axial weakness, episodic vomiting, and easy fatigue. Early treatment with dietary regulations, high-dose riboflavin, carnitine supplementation in those with carnitine deficiency, and coenzyme Q10 supplementation is life-saving.
Keywords: MADD, metabolic myopathy, ETFDH, episodic vomiting