Abstract: TH-PO658

A Novel SLC12A1 Compound Heterozygous Mutation in Antenatal Bartter Syndrome Type 1 Showing Benign Clinical Course

Session Information

  • Pediatric Nephrology
    November 02, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Developmental Biology and Inherited Kidney Diseases

  • 403 Pediatric Nephrology

Authors

  • Kiuchi, Zentaro, Kyorin University School of Medicine, Tokyo, Japan
  • Nozu, Kandai, Kobe University, Kobe, Japan
  • Yan, Kunimasa, Kyorin University School of Medicine, Tokyo, Japan
Background

[Introduction]Antenatal Bartter syndrome (BS) type 1 is an autosomal recessive kidney disorder that shows severe renal dysfunction caused by loss-of-function mutations in the solute carrier family 12 member 1 (SLC12A1) gene.

Methods

[Case Description]This case is currently a 2 year-old girl. At 24 weeks of gestation, she had polyhydramnios in utero. She was born by vaginal delivery at 33 weeks 3 days. Polyuria (5-7ml/kg/hr) was observed from at the age of 1 day, accompanied by hyponatremia and hypokalemia and mild metabolic alkalosis. Urine osmotic pressure was always under 200mOsm/L. She had high reninemia and hyperaldosteronism. There was no morphological abnormality in kidney ultrasonography. Abdominal CT did not show kidney calcification. She had no hypertension or edema, but she suffered from failure to thrive (body length –2.1SD, body weight -2.7SD). Her psychomotor development is currently normal and growth is becoming to be within normal range. Analysis of the SLC12A1 gene demonstrated heterozygous mutation consisting of 2 novel mutations: c.2094delG in exon16 from father and c.1094T>C (p.I365T) in exon8 from mother, which led to the final diagnosis as BS type 1. Currently she receives treatment with oral medications including NaCl, KCl, Spironolactone and Alfacalcidol.

Conclusion

[Discussion]We here present an antenatal BS type 1 caused by novel heterozygous mutations of the SLC12A1 gene. c.2094delG leads to the final formation of the protein mass of 75 kDa compared to the mature mass of 120 kDa. This immature mass is predicted to interfere homo-oligomer formation. On the other hand, the functional influence of p.I365T is not able to speculate so far. However, this report clearly indicates that a combination of heterozygous mutation found in our case would not severely impact on the renal tubular function after birth even in the cases with antenatal Bartter syndrome type1.