A Myopathy, Lactic Acidosis, Sideroblastic Anemia (MLASA) Case Due to a Novel PUS1 Mutation

The patient, the first child of Turkish first-cousins, was born at term after an uncomplicated pregnancy. Birth parameters were normal. The family history was negative for hematological or neurological diseases. The newborn period was characterized by hypoglycemia, lactic acidemia (6.1 mmol/L; normal values: up to 1.9 mmol/L), and lactic, pyruvic, and dicarboxylic aciduria. At 10 months of age, hematological examination revealed marked sideroblastic anemia. He started to receive transfusions every 3-4 weeks until 14 months of age, when the blood parameters spontaneously normalized. He had exercise intolerance and delayed motor milestones (walking at 3.5 years of age). At 14 years of age, pallor, progressive muscle weakness, and lethargy occurred and sideroblastic anemia reappeared. The boy had mild mental insufficiency, profound generalized hypotrophy and weakness, and hyperlordosis of the trunk. He became transfusion-dependent, requiring packed cell transfusions every 2-3 weeks. The muscle biopsy showed subsarcolemmal abnormal mitochondrial aggregates and diffuse negative staining for cytochrome c oxidase. Due to the paucity of tissue, the biochemical evaluation of respiratory chain complexes was not performed. The clinical features oriented us towards a mitochondrial pathology; CoQ10 was given (400 mg/day) and dramatic improvement of muscle strength was observed with reduction of the frequency of blood transfusions. Unfortunately, the boy died when he was 18 years old due to severe respiratory failure.