Primary disorders of carnitine metabolism often show an autosomal recessive pattern of inheritance. Primary disorders of carnitine metabolism include mutations in OCTN2 carnitine transporter.
A patient who develops a secondary carnitine deficiency may also have onset of heart disease or unexplained worsening of an existing cardiac disorder.
An affected patient may show:
(1) heart failure poorly responsive to standard therapy with diuretics and inotropes
(2) ventricular arrhythmias that can result in sudden death
The patient may have:
(1) cardiac hypertrophy (may be only evidence in a patient heterozygous for a gene mutation inherited as autosomal recessive disorder)
(2) a dilated cardiomyopathy
A patient with a primary or secondary disorder involving carnitine may:
(1) present with an isolated cardiomyopathy
(2) have disorders of both heart and skeletal muscle
(3) have a systemic disorder with cardiac involvement a major or minor component
The possibility of a disorder of carnitine metabolism should be considered:
(1) in children or adults with unexplained heart failure and/or ventricular arrhythmia
(2) if there is a family history of heart failure or cardiomyopathy
(3) if the patient a patient with risk factors for carnitine deficiency develops heart failure or a ventricular arrhythmia
The blood levels of carnitine may be reduced in a patient with a carnitine deficiency. A patient with primary defect in a transport molecule may have normal blood levels.
