Coenzyme Q10 deficiency with renal involvement: a newly characterized disorder
Original article
Diomedi-Camassei F et al. (2007) COQ2 nephropathy: a newly described inherited mitochondriopathy with primary renal involvement. J Am Soc Nephrol 18: 2773–2780 PubMed
Primary coenzyme Q10 (CoQ10, or ubiquinone) is vital for mitochondrial energy production. Deficiency of this enzyme normally manifests as neurological and muscular symptoms. Diomedi-Camassei and colleagues describe the first four cases of primary CoQ10 deficiency with renal involvement, linking the disorder to novel mutations of the COQ2 gene that encodes the para-hydroxybenzoate–polyprenyltransferase enzyme of the CoQ10 synthesis pathway. They propose that inherited mutations in COQ2 cause a primary glomerular disease—"COQ2 nephropathy"—characterized by renal lesions of varying severity and proliferation of dysmorphic mitochondria, but not necessarily neurological manifestations.
Patients were between 6 months and 2 years of age when studied. They had presented with isolated nephrotic syndrome, steroid-resistant nephrotic syndrome (associated with progressive encephalomyopathy in one case) or neonatal renal failure. Genetic analyses detected a homozygous c437G>A mutation, two homozygous c890A>G mutations (harbored by a sibling pair, who had previously been reported), and a combined heterozygous mutation (c590G>A and c683A>G). Electron microscopy of renal tissue from all four patients revealed increased numbers of abnormal mitochondria in glomerular cells, particularly podocytes. Biochemical analysis of skeletal muscle and renal cortex showed decreased activity of respiratory chain complexes II and III and low levels of CoQ10. COQ2 mutations were absent from the 500 control DNA samples analyzed, and from four patients with CoQ10 deficiency but no renal involvement.
Early identification of COQ2 nephropathy could, say the authors, enable prompt initiation of ubiquinone supplementation.
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Subject areas under which this article appears: Genetics of renal disease | Glomerular diseases (glomerulonephritis, FSGS, cryoglobulinemia)
