Carnitine palmitoyltransferase II deficiency

Carnitine palmitoyltransferase II deficiency, sometimes shortened to CPT-II or CPT2, is an autosomal recessively inherited genetic metabolic disorder characterized by an enzymatic defect that prevents long-chain fatty acids from being transported into the mitochondria for utilization as an energy source. The disorder presents in one of three clinical forms: lethal neonatal, severe infantile hepatocardiomuscular and myopathic.

First characterized in 1973 by DiMauro and DiMauro, the adult myopathic form of this disease is triggered by physically strenuous activities and/or extended periods without food and leads to immense muscle fatigue and pain. It is the most common inherited disorder of lipid metabolism affecting the skeletal muscle of adults, primarily affecting males. CPT II deficiency is also the most frequent cause of hereditary myoglobinuria.

Signs and symptoms

The three main types of carnitine palmitoyltransferase II deficiency are classified on the basis of tissue-specific symptomatology and age of onset. Among the few people diagnosed with CPT2, some have unknown and/or novel mutations that place them outside these three categories while remaining positive for CPT2.

Neonatal form

The neonatal form is the least common clinical presentation of this disorder and is almost invariably fatal in rapid fashion regardless of intervention. Symptomatic onset has been documented just hours after birth to within 4 days of life. Affected newborns typically experience respiratory failure, low blood sugar, seizures, liver enlargement, liver failure, and heart enlargement with abnormal heart rhythms leading to cardiac arrest.