Hereditary protein C deficiency associated with riboflavin-responsive lipid storage myopathy

We report a 14 year old patient who presented lung emboli and deep vein thrombosis in relationship to protein C deficiency. He had a carnitine-deficient lipid myopathy. Fresh muscle homogenate showed low activities in oxidizing [1-¹⁴C]-butyrate, [1-¹⁴C]-octonoate and [1-¹⁴C]-palmitate. A deficient short chain butyryl-CoA dehydrogenase (SCAD) was found in isolated muscle mitochondria. The patient improved dramatically with daily therapy of 200 mg riboflavin, 2 g carnitine and anticoagulation with coumadin. The treatment was found to restore fatty acid oxidation in fresh muscle homogenate, deficient acylCoA-dehydrogenases in mitochondria and decrease lipid droplets. These results suggest that in this type of lipid myopathy riboflavin supplementation may be effective. The link with protein C deficiency is discussed.