Lactate dehydrogenase deficiency type A

Lactate Dehydrogenase Deficiency Type A (LDHA deficiency) is a rare metabolic disorder characterized by a deficiency in the enzyme lactate dehydrogenase A (LDHA), which is crucial for the anaerobic metabolism of glucose to lactic acid. This condition is part of a group of disorders known as glycogen storage diseases which affect the way the body uses sugar for energy. LDHA deficiency is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to be affected by the disorder.

Symptoms and Diagnosis

The symptoms of LDHA deficiency can vary widely among affected individuals but commonly include muscle cramps, fatigue, and pain following vigorous exercise due to an inability to adequately produce lactic acid under anaerobic conditions. Unlike other forms of glycogen storage diseases, individuals with LDHA deficiency typically do not experience myoglobinuria (presence of myoglobin in urine) after exercise.

Diagnosis of LDHA deficiency involves a combination of clinical evaluation, family history, and laboratory tests. These tests may include enzyme assays to measure the activity of lactate dehydrogenase in red blood cells or muscle tissue, and genetic testing to identify mutations in the LDHA gene.

Treatment and Management

There is no cure for LDHA deficiency, and treatment is symptomatic and supportive. Management strategies may include avoiding strenuous exercise to prevent muscle cramps and pain, and dietary modifications to ensure adequate energy supply during activities. In some cases, supplementation with oral bicarbonate or other buffers may help to manage symptoms by compensating for the reduced lactic acid production.

Genetics

LDHA deficiency is caused by mutations in the LDHA gene, which provides instructions for making the A isoform of lactate dehydrogenase. This enzyme plays a key role in the conversion of pyruvate, a product of glucose metabolism, to lactate when oxygen levels are low. Mutations in the LDHA gene reduce or eliminate the activity of the enzyme, disrupting this critical metabolic pathway.

Epidemiology

LDHA deficiency is an extremely rare condition, with only a few cases reported in the medical literature worldwide. Due to its rarity, the exact prevalence of the disorder is unknown.

See Also

• Glycogen storage disease
• Metabolic disorder
• Anaerobic metabolism
• Genetic testing

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