Late Diagnosis of Adult-Onset Carnitine Palmitoyltransferase II Deficiency in a 63-Year-Old Man Presenting with Recurrent Rhabdomyolysis: A Case Report

<title>Abstract</title> <p>Carnitine palmitoyltransferase II (CPT II) deficiency is one of the most common disorders of long-chain fatty acid oxidation presenting in adulthood and is characterized by recurrent episodes of rhabdomyolysis, myalgia, and transient muscle weakness. Because the clinical manifestations are episodic and neurological examination and electromyography findings are often normal during asymptomatic periods, diagnosis is frequently delayed. Herein, we report the case of a 63-year-old man who had been followed since 2011 for persistent creatine kinase elevation and recurrent episodes of rhabdomyolysis. Although he had initially been diagnosed with myositis, persistent creatine kinase elevation, recurrent attacks, and normal neurological findings between episodes prompted further evaluation for a metabolic myopathy. Comprehensive genetic testing identified a homozygous CPT2 c.338C &gt; T (p.Ser113Leu) variant, confirming the diagnosis of adult-onset CPT II deficiency. Following the diagnosis, the patient received dietary counseling and was advised to avoid prolonged fasting, strenuous exercise, and other known precipitating factors. This case highlights that CPT II deficiency should be considered in adults presenting with recurrent rhabdomyolysis and persistent creatine kinase elevation, regardless of age, and emphasizes the importance of early molecular genetic testing to establish the diagnosis, prevent unnecessary investigations, and facilitate appropriate management.</p>