3-hydroxyacyl-coenzyme A dehydrogenase deficiency

3-Hydroxyacyl-Coenzyme A Dehydrogenase Deficiency (HADH deficiency) is a rare metabolic disorder that affects the body's ability to oxidize fatty acids to produce energy. This condition is part of a group of disorders known as fatty acid oxidation disorders. It is caused by mutations in the HADH gene, which encodes the enzyme 3-hydroxyacyl-CoA dehydrogenase involved in the mitochondrial fatty acid beta-oxidation pathway. This enzyme is crucial for converting medium and short-chain hydroxyacyl-CoAs into their corresponding 3-ketoacyl-CoAs. The deficiency leads to an accumulation of medium-chain fatty acids and their metabolites, which can be toxic and result in metabolic crises.

Symptoms and Presentation

Individuals with HADH deficiency may present with a wide range of symptoms, which can vary significantly in severity. Common symptoms include hypoglycemia (low blood sugar), lethargy, cardiomyopathy (heart muscle disease), muscle weakness, and liver dysfunction. In infants, the disorder may manifest as episodes of hypoketotic hypoglycemia, which means low blood sugar levels occur without the expected increase in ketone bodies, typically seen in fasting states or energy crises.

Diagnosis

Diagnosis of HADH deficiency involves a combination of clinical evaluation, biochemical tests, and genetic testing. Biochemical tests may reveal elevated levels of specific metabolites in the blood or urine, indicative of a block in fatty acid oxidation. Genetic testing can confirm the presence of mutations in the HADH gene.

Treatment

Management of HADH deficiency focuses on preventing metabolic crises and involves regular feeding schedules, avoidance of fasting, and a diet low in medium-chain triglycerides. During illness or times when oral intake is reduced, intravenous glucose may be necessary to prevent hypoglycemia. Carnitine supplementation may also be beneficial, as it can help in the transport of fatty acids into mitochondria for oxidation and energy production.

Prognosis

The prognosis for individuals with HADH deficiency varies depending on the severity of the condition and the effectiveness of the management strategies. Early diagnosis and intervention can significantly improve outcomes and reduce the risk of severe metabolic crises.