Carnitine Palmitoyltransferase II Deficiency
Carnitine palmitoyltransferase II is an enzyme localized in the inner mitochondrial membrane, where it takes part in the transport of long-chain fatty acids into the mitochondrial matrix. Following its first description in 1973, CPT-II deficiency is the most common disorder of lipid metabolism. Three different clinical phenotypes can be associated with CPT-II deficiency: one muscle form restricted to skeletal muscle with juvenile-adult onset; one severe, infantile-onset form with hepatic, skeletal, and cardiac muscle involvement; and one fatal, neonatal-onset form with dysmorphic abnormalities. In the most frequent muscle form, the clinical hallmark consists in recurrent attacks of myalgias and cramps, often associated with myoglobinuria. Rhabdomyolytic episodes are usually triggered by prolonged exercise, fasting, fever, infection, high fat intake, and exposure to cold, heat shock, emotional stress, and drugs. They may be complicated by life-threatening events, including acute renal failure, respiratory failure, and, more rarely, cardiac arrhythmias and hypoglycemia. CPT-II deficiency can be diagnosed by the determination of CPT activity in muscle, platelets, or fibroblasts. A definite diagnosis requires the identification of mutations in the CPT2 gene (Table 64.1); among Caucasian patients, the p.S113L mutant allele recurs with 60–68 % frequency.
KeywordsMyoglobinuria Myalgia Cold and fever as triggering factors
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