Aims: To create awareness of adult-onset carnitine palmitoyltransferase II (CPT II) deficiency by describing the clinical, biochemical, and genetic features of three New Zealand patients with this disorder.
Methods: Review of case notes, creatine kinase (CK) values, CPT II assay results, genetic mutation analyses, and the literature.
Results: Three patients with CPT II deficiency were encountered by the authors over a 7-year period. Onset of symptoms was between ages 10 and 17 years. Each patient reported exertional myalgia, and had had at least two episodes of myoglobinuria following exertion or infection. Interictal neurological examinations, CK values, and routine muscle histology were normal. CPT II activities ranged from 3.8 to 9.7 pmol/min/mg protein (normal+/-SD=162.9+/-51.0 pmol/min/mg protein). Genetic analysis showed that one patient was homozygous and two were heterozygous for S113L, the common mutation in CPT II deficiency.
Conclusions: CPT II deficiency should be suspected in patients with persistent exertional myalgia who have one or more episodes of myoglobinuria. The diagnosis is confirmed using a combination of enzyme assay and genetic testing.