Genetic Disorders and Biochemical Pathology — MCQs

Question 791: Which of the following statements is NOT true about medium chain acyl-CoA dehydrogenase deficiency?

• A. Autosomal recessive inheritance
• B. Cardiomyopathy (Correct Answer)
• C. Hypoketotic hypoglycemia
• D. Episodes associated with fasting

Explanation: ***Cardiomyopathy*** - While other fatty acid oxidation disorders can present with **cardiomyopathy**, Medium Acyl-CoA Dehydrogenase Deficiency (MCADD) primarily affects the **liver** and **skeletal muscle**, not the heart. - The classic presentation involves episodes of **hypoketotic hypoglycemia** and **lethargy**, often triggered by fasting or illness. *Autosomal recessive inheritance* - MCADD is indeed inherited in an **autosomal recessive pattern**, meaning an individual must inherit two copies of the mutated gene (one from each parent) to be affected. - This is a characteristic feature of many **inborn errors of metabolism**, including fatty acid oxidation disorders. *Hypoketotic hypoglycemia* - This is a hallmark feature of MCADD, as the body cannot effectively break down **medium-chain fatty acids** into ketones for energy during periods of fasting. - The buildup of toxic intermediates and lack of ketosis contribute to the acute metabolic crises observed in affected individuals. *Episodes associated with fasting* - Fasting is a common trigger for metabolic decompensation in MCADD, as the body becomes reliant on **fatty acid oxidation** for energy when glucose stores are depleted. - Illnesses that reduce appetite or increase energy demands, leading to prolonged fasting, can precipitate acute crises.