Background: Steroid-resistant nephrotic syndrome (SRNS) is a common problem in paediatric nephrology practice which tends to progress to end-stage renal disease. SRNS-causing genes are expressed in the glomerular podocyte which is a specialized cell type. However, there are more than 80% of SRNS cases with unknown molecular etiology. Coenzyme Q10 (CoQ10) has an important role in the mitochondrial electron-transport chain. Synthesis of CoQ10 is a complex pathway, involving enzymes from various genomes; termed from CoQ1 to CoQ10. Due to sequenced reactions of synthesis, enzymes and regulatory proteins are needed in obligation. So any dysfunction here; affects the biosynthesis of CoQ10.
Aim: We here described quinone-responsive six patients having CoQ2 mutations, presented with steroid-resistant NS.
Findings: CoQ 10 deficiency is strongly related with CoQ2 deficiency and/or any mutation of encoding genes. Among the 5 types of CoQ 10 deficiency, infantile form can be presented only with renal involvement, nephrotic syndrome. Also in other forms, renal involvement is not rare besides the neurological pathologies. All 6 cases of us with CoQ2 mutation responded to CoQ 10 treatment.
Conclusions: In conclusion, early recognition of CoQ2 nephropathy is crucial. CoQ10 supplementation improves the clinical symptoms and prevents neurologic complications. Long-term follow-up is important to define the prognosis of these patients.
Key words: CoQ 10, CoQ2 nephropathy, SRNS, quinone, children, mutation