肌肉β-烯醇酶缺乏所致糖原贮积症（Glycogen storage disease due to muscle beta-enolase deficiency）

Glycogen storage disease due to muscle beta-enolase deficiency (GSD-MBE) is an extremely rare metabolic disorder characterized by a deficiency of the muscle-specific isoform of the enzyme beta-enolase, which is essential for glycolysis. This condition has been reported in only one case to date, highlighting its rarity. The primary clinical features include exercise intolerance and muscle pain, which are attributed to the severe deficiency of beta-enolase in muscle tissue.

疾病机制

Glycogen storage disease due to muscle beta-enolase deficiency is caused by a mutation in the ENO3 gene, which encodes the muscle-specific isoform of the enzyme beta-enolase. Beta-enolase is a key enzyme in the glycolytic pathway, responsible for the conversion of 2-phosphoglycerate to phosphoenolpyruvate. A deficiency of this enzyme disrupts the normal glycolytic process, leading to an accumulation of glycogen in muscle cells and impairing energy production during physical activity.

临床表现

The clinical presentation of GSD-MBE is characterized by exercise intolerance and muscle pain. Patients may experience severe fatigue and weakness after minimal physical exertion. Muscle cramps and myalgia are also common. The condition is typically diagnosed in childhood or adolescence, as symptoms become more apparent with increasing physical activity.

诊断

Diagnosis of GSD-MBE is based on clinical presentation, biochemical testing, and genetic analysis. Elevated levels of lactate and pyruvate in muscle biopsies, along with reduced levels of phosphoenolpyruvate, suggest a defect in the glycolytic pathway. Genetic testing for mutations in the ENO3 gene can confirm the diagnosis.

遗传咨询

GSD-MBE is inherited in an autosomal recessive manner. This means that both parents must carry a mutation in the ENO3 gene to pass the condition on to their child. Genetic counseling is recommended for families with a history of the condition to understand the risk of recurrence and to explore prenatal testing options.

预后

Due to the rarity of GSD-MBE, there is limited data on long-term prognosis. Management focuses on symptom relief and avoidance of strenuous physical activity to prevent exacerbation of symptoms. Regular monitoring and supportive care are essential to maintain quality of life. Research into potential therapeutic interventions is ongoing, but currently, there is no cure for the condition.