Martín-Hernández E et al. (2005) Renal pathology in children with mitochondrial diseases. Pediatr Nephrol 20: 1299–1305

Patients with mitochondrial diseases often present with renal impairment. A recent systematic study of kidney function in children with defective mitochondria has confirmed this association, and enhanced our comprehension of the genetics behind it.

Kidney dysfunction was detected in 50% of the 42 children (average age 5.2 years) with previously diagnosed mitochondrial diseases, such as encephalomyopathy, KEARNS–SAYRE SYNDROME and PEARSON SYNDROME, who were included in the study. Renal impairment—for example Fanconi's syndrome, chronic renal failure and focal segmental glomerulosclerosis—was severe in eight patients. The remaining patients with renal involvement had mild tubular disorders only, and no apparent symptoms.

Single deletions of mitochondrial DNA were harbored by six children with renal disorders (four with Fanconi's syndrome); most of these patients had been diagnosed with either Kearns–Sayre syndrome or Pearson syndrome. No single mitochondrial DNA deletions were found in patients with normal kidney function.

Martín-Hernández et al. recommend that, when diagnosing patients with tubulopathy of unknown origin and progressive renal involvement with symptoms involving other organs and tissues, nephrologists consider an underlying mitochondrial disorder. In young mitochondrial disease sufferers, kidney function should be assessed, and molecular studies performed, to enhance clinical outcomes and improve understanding of the relationship between the genetics of mitochondrial disorders and renal pathology.