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Abstract: PO1632

Clinical Manifestations and Mutation Analysis of Idiopathic Renal Hypouricemia

Session Information

Category: Genetic Diseases of the Kidneys

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Mou, Lijun, Nephrology Department. Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
  • Chen, Xujiao, Nephrology Department. Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
  • Hu, Ying, Nephrology Department. Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
Background

Idiopathic renal hypouricemia (RHUC), was thougt an autosomal recessive inheritancea disorder, characterized by impaired uric acid (UA) reabsorption in the proximal tubule and subsequent profound hypouricemia, caused by mutations in SLC22A12 or SLC2A9. Most cases of RHUC were reported in Japan, only a few have been detected in China. A retrospective analysis was performed in this study to report the clinical manifestations and genetic mutation profiles of RHUC patients in China.

Methods

The medical history, clinical manifestations, biochemical and genetic data, clinical outcomes of Chinese patients with RHUC were collected in this study.

Results

Seven male and two female patients were diagnosed with idiopathic RHUC according to the criteria: serum uric acid(SUA) level of ≤120μmol/L,fractional excretion of uric acid (FEUA) and exclusion of other diseases that present hypouricemia as a symptom. The median age of onset were 30 (11~48) years old. The median levels of SUA was 83(5~95)μmol/L, the median FEUA was 29%(26.6%~346.83%). Homozygous SLC2A9 mutations were identified in two male patients, homozygous mutations in SLC22A12 in two patients, compound heterozygous mutations in SLC22A12 in one patient, heterozygous mutations in SLC22A12 in four patients. Exercise-induced acute kidney injury(EIAKI) developed in six patients ,including the two patients with mutations in SLC2A9, the patient with compound heterozygous mutations in SLC22A12,one patient with homozygous mutations in SLC22A12, two patients with heterozygous mutations in SLC22A12.The two female patients were asymptomatic and the patients with EIAKI were all male. Two patients with heterozygous mutations in SLC22A12 had nephrolithiasis. Two patients had recurrent EIAKI whereas the renal function of all patients with EIAKI returned to normal. Strenuous exercise was strictly prohibited. Over the median 40 (7~233) months follow-up, no patient developed EIAKI again.

Conclusion

SLC22A12 mutations were more common than SLC2A9 mutations in Chinese patients with RHUC, EIAKI only developed in male patients. Heterozygous mutations in SLC22A12 also resulted in hypouricemia, EIAKI and nephrolithiasis. The prognosis of RHUC was favorable.

Funding

  • Government Support - Non-U.S.