Adult patients deficient in
carnitine palmitoyltransferase II (
CPT II) cannot generate sufficient amounts of energy, which results in
rhabdomyolysis and
acute renal failure (ARF). Its genetic basis has been recognized; but histopathologic changes, especially electron microscopic changes, have scarcely been described. The study subject is a patient with ARF caused by repetitive nontraumatic
rhabdomyolysis. The
acylcarnitine profile of serum and
enzyme assay on skin fibroblasts confirmed the diagnosis of
CPT II deficiency. Renal biopsy specimens were examined microscopically and immunohistochemically. The histological diagnosis was
interstitial nephritis with acute tubular
necrosis caused by
rhabdomyolysis.
Myoglobin in tubules was detected by means of immunohistochemistry and electron microscopy. The genetic structure of
CPT II was analyzed in the patient and his family. Eight pairs of polymerase chain reaction (PCR) primers were designed to cover the coding region. Each PCR-amplified gene product was subjected to
DNA sequencing, which unveiled heterozygosity at the
CPT II locus consisting of a deletion of
cytosine and
thymine at
codon 408, resulting in a stop signal at 420, as well as a mutation of
arginine to
cysteine at
codon 631. The frame shift at 408 has never been described before.
DNA sequencing of the family showed the deletion mutation from the mother and the point mutation from the father. We describe renopathological findings in a patient with
CPT II deficiency associated with
rhabdomyolysis, which suggested the pathological role of
myoglobin casts in the development of tubular
necrosis. Genetic analysis of the patient identified a novel variant of the
CPT II gene.