Renal tubular involvement mimicking Bartter syndrome in a patient with Kearns-Sayre syndrome.
A 10-year-old boy had short stature, external ophthalmoplegia, atypical retinal pigmentary degeneration, and sensorineural hearing loss (Kearns-Sayre syndrome). In addition to ragged-red fibers observed on modified Gomori trichrome staining, there were scattered fibers exhibiting no cytochrome c oxidase activity, indicating a focal deficiency. Cytochrome c oxidase and other respiratory chain enzyme activities were normal biochemically. The patient also had renal tubular dysfunction, including isosthenuria, decreased urine-concentrating ability, and excessive excretion of potassium and magnesium. In addition, he had hyperreninemia and hyperaldosteronism but no hypertension. The renal dysfunction was thought to have resulted from a primary defect in the thick ascending limb of the loop of Henle, mimicking Bartter syndrome. In contrast to previously described cases of cytochrome c oxidase deficiency with de Toni-Fanconi Debré syndrome, the patient had less intensive muscle abnormalities. A renal biopsy specimen showed ultrastructural changes in mitochondria that were similar to those seen in biopsy specimens of muscle. A large-scale deletion (8.8 kilobases) in mitochondrial DNA was found in biopsy specimens of muscle and kidney.
Goto
Y
Y
Department of Pediatrics, Hokkaido University School of Medicine, Sapporo, Japan.
Itami
N
N
Kajii
N
N
Tochimaru
H
H
Endo
M
M
Horai
S
S
D001477:Bartter Syndrome / Q000473:pathology*; D002648:Child; D030401:Cytochrome-c Oxidase Deficiency; D003937:Diagnosis, Differential; D004562:Electrocardiography; D006801:Humans; D006929:Hyperaldosteronism / Q000473:pathology*; D007625:Kearns-Sayre Syndrome / Q000473:pathology*; D007684:Kidney Tubules / Q000201:enzymology / Q000473:pathology*; D008297:Male; D008928:Mitochondria / Q000648:ultrastructure; D008931:Mitochondria, Muscle / Q000648:ultrastructure; D009132:Muscles / Q000201:enzymology / Q000473:pathology; D009886:Ophthalmoplegia / Q000473:pathology*