Cause of recurrent rhabdomyolysis, carnitine palmitoyltransferase II deficiency and novel pathogenic mutation

Carnitine palmitoyltransferase II (CPT II) deficiency is an autosomal inherited metabolic disorder in which the β-oxidation of the long chain fatty acids is defective. The clinical presentation may be in various forms; it presents itself in the severe form during neonatal and infantile periods and as the less severe myopathic form in the school age and adolescence. While the severity of the rhabdomyolysis attacks varies, occasionally the clinical course may be complicated with acute renal failure. Acylcarnitine analysis may help in the diagnosis of CPT II, but its normality does not indicate the absence of the disease. If there is strong suspicion, genetic analysis should be performed on the cases. In this article, we present a 15-year-old male patient who had two rhabdomyolysis attacks triggered by infection and starvation. Acylcarnitine analysis of the case was normal, CPT II deficiency was considered when the history was evaluated, and CPT II gene c.137A>G (p.Gln46Arg) homozygous novel pathogenic mutation was detected. CPT II deficiency is one of the most common causes of metabolic rhabdomyolysis in patients with recurrent episodes of rhabdomyolysis.

Interpretation of Acylcarnitine Analysis Results

The analysis of acylcarnitines in plasma or blood spot samples by tandem mass spectrometry will detect all 15 defects of mitochondrial fatty acid beta-oxidation, although false negative results may occur in well-fed, non-fasting patients. Moreover, more than 20 organic acidemias can be detected by this methodological approach. An acylcarnitine profile should be part of the work-up of patients presenting with rhabdomyolysis and/or hypoglycemia and adults with an unexplained leukoencephalopathy. Cases with abnormal acylcarnitines require an analysis of urine organic acids as well as enzyme activity evaluation and molecular investigations to confirm the inherited defect.