A boy with mitochondrial disease: asymptomatic proteinuria without neuromyopathy.

Abstract

Mitochondrial disorder is a relatively rare disease during childhood. Previous studies concluded that renal complications in this disease most often occur in patients with mitochondrial encephalomyopathies. We describe a boy with mitochondrial disease who presented with proteinuria while lacking neuromyopathy. Proteinuria was detected at the age of 6 years, including large amounts of low-molecular-weight proteins such as beta(2)- and alpha1-microglobulin. Renal functions were normal. Proximal tubular dysfunction and other renal manifestations were absent. Episodic neurologic problems such as migraine and nervous system diseases including epilepsy, depression, schizophrenia and amytrophic lateral sclerosis (ALS) were found in the boy's family members. Renal tubular basement membrane atrophy and interstitial fibrosis with mononuclear cell infiltration were observed. Ultrastructural examination showed mitochondria, mainly in the proximal tubules, which varied in size and had disoriented cristae. Mutation analysis using mitochondrial DNA (mtDNA) extracted from renal tissues demonstrated a A-->G point mutation at nucleotide position 3243 in the tRNA(Leu(UUR)) gene, while there was no mutation found in mtDNA extracted from peripheral leukocytes. Awareness among pediatricians of mitochondrial disorders, detection of low-molecular-weight proteinuria, renal ultrastructural examination and mutation analysis of mtDNA obtained from renal tissues could be important for early diagnosis of this disease.

• Authors: Yuka Ueda, Atsushi Ando, Taeko Nagata, Hidehiko Yanagida, Kazuro Yagi, Keisuke Sugimoto, Mitsuru Okada, Tsukasa Takemura
• Journal: Pediatric nephrology (Berlin, Germany) (Pediatr Nephrol) Vol. 19 Issue 1 Pg. 107-10 (Jan 2004) ISSN: 0931-041X [Print] Germany
• PMID: 14648337 (Publication Type: Case Reports, Journal Article)

Chemical References

• DNA, Mitochondrial
• RNA, Transfer, Leu

Topics

• Child
• DNA, Mitochondrial (analysis)
• Humans
• Kidney Diseases (complications, genetics, pathology)
• Kidney Glomerulus (pathology, ultrastructure)
• Male
• Mitochondrial Diseases (complications, genetics, pathology)
• Point Mutation
• Polymerase Chain Reaction
• Proteinuria (etiology)
• RNA, Transfer, Leu (genetics)