An ignored cause of red urine in children: rhabdomyolysis due to carnitine palmitoyltransferase II (CPT-II) deficiency

Experience with carnitine palmitoyltransferase II deficiency: diagnostic challenges in the myopathic form

OBJECTIVES

Carnitine palmitoyltransferase II (CPT II) deficiency is an autosomal recessive disorder of long-chain fatty acid oxidation. Three clinical phenotypes, lethal neonatal form, severe infantile hepatocardiomuscular form, and myopathic form, have been described in CPT II deficiency. The myopathic form is usually mild and can manifest from infancy to adulthood, characterised by recurrent rhabdomyolysis episodes. The study aimed to investigate the clinical features, biochemical, histopathological, and genetic findings of 13 patients diagnosed with the myopathic form of CPT II deficiency at Ege University Hospital.

METHODS

A retrospective study was conducted with 13 patients with the myopathic form of CPT II deficiency. Our study considered demographic data, triggers of recurrent rhabdomyolysis attacks, biochemical metabolic screening, and molecular analysis.

RESULTS

Ten patients were examined for rhabdomyolysis of unknown causes. Two patients were diagnosed during family screening, and one was diagnosed during investigations due to increased liver function tests. Acylcarnitine profiles were normal in five patients during rhabdomyolysis. Genetic studies have identified a c.338C>T (p.Ser113Leu) variant homozygous in 10 patients. One patient showed a novel frameshift variant compound heterozygous with c.338C>T (p.Ser113Leu).

CONCLUSIONS

Plasma acylcarnitine analysis should be preferred as it is superior to DBS acylcarnitine analysis in diagnosing CPT II deficiency. Even if plasma acylcarnitine analysis is impossible, CPT2 gene analysis should be performed. Our study emphasizes that CPT II deficiency should be considered in the differential diagnosis of recurrent rhabdomyolysis, even if typical acylcarnitine elevation does not accompany it.

From recurrent rhabdomyolysis in a young adult to carnitine palmitoyltransferase II deficiency

Metabolic myopathies are a diverse group of rare genetic disorders associated with recurrent episodes of rhabdomyolysis, induced by triggers such as fever or exercise. In these disorders, the energetic metabolism is compromised resulting in damage of the muscle cells. The diagnosis can be challenging but is essential for the correct treatment. Carnitine palmitoytransferase II (CPT-II) deficiency is the most common long-chain fatty acid oxidation defect, with the adulthood form requiring additional external triggers. The authors present a case of a young-male adult with recurrent episodes of rhabdomyolysis, one of them presented with acute renal failure and acute hepatitis. The diagnostic is demanding, which requires a high level of suspicion. The adequate treatment of these patients improves the muscle function and prevents other episodes of severe rhabdomyolysis.

Acute Renal Failure Secondary to an Unusual Familial Metabolic Myopathy

Rhabdomyolysis is a major cause of acute kidney failure. The etiology is diverse, from full-blown crush syndrome to less frequent causes, such as metabolic myopathy. We describe the case of a 35-year-old male with a history of intermittent myalgias who was admitted to hospital with acute renal failure secondary to rhabdomyolysis. Moderate to intense diffuse uptake of technetium-99m was seen in soft tissues at scintigraphy. The diagnosis of metabolic myopathy was confirmed after careful workup and genetic testing.