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COQ6 Mutations in Children With Steroid-Resistant Focal Segmental Glomerulosclerosis and Sensorineural Hearing Loss
Eujin Park1, Yo Han Ahn1, Hee Gyung Kang2
1Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea.
Insights
Children with steroid-resistant focal segmental glomerulosclerosis and hearing loss may have primary coenzyme Q10 deficiency. Early diagnosis of COQ6 mutations is crucial for timely treatment and improved outcomes.
Area of Science:
- Nephrology
- Genetics
- Mitochondrial Diseases
Background:
- Steroid-resistant focal segmental glomerulosclerosis (SR-FSGS) and sensorineural hearing loss are rare conditions.
- This phenotype is often associated with mitochondrial disorders, particularly primary coenzyme Q10 (CoQ10) deficiency.
Observation:
- A study of 10 children with SR-FSGS and sensorineural hearing loss identified 6 patients with biallelic COQ6 mutations.
- Nephrotic syndrome onset was at a median of 29 months, with progression to end-stage renal disease within 13 months.
- Kidney biopsies showed abnormal mitochondrial proliferation in podocytes in all affected patients.
Findings:
- Biallelic COQ6 mutations were identified in 6 out of 10 children with SR-FSGS and sensorineural hearing loss.
- All patients with identified mutations experienced rapid progression to end-stage renal disease.
- No recurrence of FSGS was observed in kidney transplant recipients.
Implications:
- Primary CoQ10 deficiency due to COQ6 mutations should be considered in children with this combined phenotype.
- Early diagnosis and CoQ10 supplementation are essential for potentially treating the condition.
- Early kidney biopsy to detect mitochondrial abnormalities may aid in earlier diagnosis.
Abstract:
The phenotypic combination of steroid-resistant focal segmental glomerulosclerosis (SR-FSGS) and sensorineural hearing loss has been mainly reported in patients with mitochondrial cytopathies, including primary coenzyme Q10 (CoQ10) deficiency. In this report of 10 children with SR-FSGS and sensorineural hearing loss, we found 6 patients with biallelic COQ6 mutations. Median age at the onset of nephrotic syndrome was 29 (range, 15-47) months. All patients progressed to end-stage renal disease within a median of 13 (range, 1-27) months after the onset. Kidney biopsy revealed abnormal mitochondrial proliferation in podocytes in all 6 patients. None of the 5 patients who underwent kidney transplantation developed recurrence of FSGS. Primary CoQ10 deficiency due to COQ6 mutations should be considered in children presenting with both SR-FSGS and sensorineural hearing loss. An early diagnosis of COQ6 mutations is essential because the condition is treatable when CoQ10 supplementation is started at the early stage. We recommend early kidney biopsy because detection of abnormal mitochondrial proliferation in podocytes might provide an earlier diagnostic clue.
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