Rhabdomyolysis caused by carnitine palmitoyltransferase 2 deficiency: A case report and systematic review of the literature

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.

Myopathic Carnitine Palmitoyltransferase II (CPT II) Deficiency: A Rare Cause of Acute Kidney Injury and Cardiomyopathy

Carnitine palmitoyltransferase II (CPT II) deficiency is a long-chain fatty acid (LCFA) oxidation disorder. There are three main types classified by symptoms and age of onset: the neonatal form, the infantile hepatocardiomuscular form, and the adult or myopathic form. The first two are early-onset severe disorders presenting with marked hypoketotic hypoglycemia, cardiomyopathy, and liver dysfunction. The latter is characterized by muscle pain and weakness and stiffness, typically triggered by exercise or febrile illnesses and occasionally associated with myoglobinuria. One of the most common complications is acute kidney injury (AKI) following massive rhabdomyolysis, which is managed with aggressive fluid therapy; crystalloid solutions are preferred. We report an otherwise healthy 38-year-old patient who presented with severe myalgia, cramps, fatigue, low-grade fever, and transient myoglobinuria, after intense physical training. Significant recurrent muscle pain was reported. Family history was unremarkable. Imaging studies showed no abnormalities. Echocardiogram showed a left ventricle ejection fraction (LVEF) of 40%. Acetylcarnitine analysis with tandem mass spectrometry and molecular tests confirmed the diagnosis. Fluid resuscitation was started. Acute kidney injury was diagnosed and managed with plasmapheresis and five sessions of hemodialysis. The patient was discharged upon the improvement of renal function with lifestyle modification recommendations. In otherwise healthy young adults presenting with myalgia and rhabdomyolysis triggered by physical activity or infection, CPT II deficiency should be considered, and genetic testing should be initiated to provide an opportunity for patients to modify their daily lifestyle, preventing future attacks and the development of complications.

Mitochondrial Fatty Acid Beta-Oxidation Disorders in Children: Literature Review

Congenital mitochondrial fatty acid beta-oxidation disorders are a heterogeneous group of metabolic disorders characterized by impaired fatty acid metabolism in mitochondria. It results in central nervous system, skeletal muscle, cardiovascular system, and liver damage, as well as the development of nonketotic hypoglycemia. The age of disease manifestation and its severity range from severe (neonatal) to milder myopathic (adult) forms. The extension of the mass screening program in Russian Federation allows to detect these diseases during the first weeks of life. The availability of effective therapy for mitochondrial fatty acid beta-oxidation disorders, especially during early diagnosis, enables timely stabilization of the patient's condition and prevention of severe complications. Awareness of pediatricians, neonatologists, neurologists, and cardiologists about such diseases is the urgent task of modern pediatrics.

Rhabdomyolysis Associated with Recent SARS-COV-2 Infection in a Patient with Carnitine Palmitoyltransferase II Deficiency

Carnitine palmitoyltransferase II deficiency (CPT II) is an autosomal recessive inherited disorder of long-chain fatty acid oxidation in the mitochondrial matrix, resulting in an inability to utilize fat for energy in cells. The most frequent myopathic form occurs in young adults and is associated with recurrent episodes of exercise-induced rhabdomyolysis. The myopathic form is caused by the Ser113Leu mutation of the CPT II gene. Rarely, massive rhabdomyolysis could be complicated by acute kidney injury (AKI), cardiomyopathy, and respiratory insufficiency. We present a case of an 18-year old male with myalgia, muscular weakness, and dark-colored urine after prolonged exercise and a recent mildSARS-CoV-2infection. Massive rhabdomyolysis was diagnosed with markedly increased serum concentrations of myoglobin and creatine kinase, with normal kidney function. The patient experienced two similar episodes in the years 2017 and 2018, with rhabdomyolysis and AKI treated with hemodialysis. After excluding autoimmune and infectious diseases as causes of recurrent rhabdomyolysis, the patient was genetically tested and Ser113Leu mutation of the CPT II gene was confirmed. When a patient presents with myalgia and dark-colored urine triggered by minor physical activities, genetic testing for possible CPT II deficiency should be initiated. TheSARS-CoV-2infection could be a factor that triggers the occurrence of rhabdomyolysis and aggravates the severity of the attack in patients with CPT II deficiency.

Severe rhabdomyolysis in homozygote carnitine palmitoyltransferase II deficiency

Carnitine palmitoyltransferase II (CPT II) deficiency represents an inherited defect in mitochondrial long-chain fatty acid oxidation. Rhabdomyolysis with necrosis of muscle is caused by the destruction of skeletal muscle and leads to systemic, multiorgan complications due to the release of intracellular muscle components. Severe rhabdomyolysis may be triggered by combination of a genetic predisposition, including CPT II deficiency, with additionally acting causes. Generally, patients with CPT II deficiency are rarely clinical recognized and reported. We describe a patient presenting severe rhabdomyolysis due to urosepsis, who, in genetic testing, demonstrated the homozygous CPT II deficiency (c.338C>T, p.Ser113Leu) mutation. The diagnosis of CPT II deficiency helped this patient to put the symptoms into context, and this reduced myopathy and the risk of recurring rhabdomyolysis. We report on this patient to increase awareness of diagnostic and medical management in CPT II deficiency.