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Abstract: TH-PO724

Blood Pressure and Biological Phenotype in Healthy-Carrier Relatives of Patients with Gitelman Syndrome

Session Information

Category: Genetic Diseases of the Kidney

  • 1002 Genetic Diseases of the Kidney: Non-Cystic

Authors

  • Vargas-Poussou, Rosa, AP-HP Hôpital Européen Georges Pompidou, Paris, France
  • Dubourg, Laurence, hospices civils de Lyon -Université Claude Bernard Lyon 1-INSERM U 820, LYON, France
  • Vallet, Marion, Hôpital Rangueil, Toulouse, France
  • Allard, Julien, University Hospital Limoges, LImoges, France
  • Haymann, Jean-philippe, Sorbonne Universit?, INSERM, UMR_S 1155, AP-HP, H?pital Tenon, Paris, France, Paris, France
  • De la faille, Renaud, Hopital Pellegrin, Bordeaux, France
  • Baron, Stephanie, APHP Georges Pompidou european Hospital, PARIS, France
  • Houillier, Pascal, Paris Descartes University, Paris, France
  • Tack, Ivan A., Universite Paul SABATIER Toulouse III/Service Explorations Fonctionnelles Physiologiques, Toulouse Cedex 9, France
  • Blanchard, Anne, APHP, HEGP, Paris, France
Background

Gitelman syndrome (GS) is the most frequent salt-losing tubulopathy caused by loss of function mutations in the SLC12A3 gene, encoding for the thiazide-sensitive NaCl cotransporter. Depending on the country, 1 to 4 % of the population is heterozygous carrier of pathogenic variant. Consequence of this status remains debated. The aim of this study was to evaluate the impact of SLC12A3 heterozygous mutations on blood pressure (primary outcome) and on electrolyte and glucose homeostasis.

Methods

This cross-sectional study included 239 subjects, both sex, 18-75 years old: 81 heterozygous carriers (HC) of class 4-5 variants (ACMG 2015), 81 non-carrier normotensive subjects (NC) matched to HC on age, sex and BMI and 77 patients with genetically proven GS. Home blood pressure (HBP) measurements were done the 3 consecutive days before admission in hospital for blood and urine sampling and oral glucose tolerance test (OGTT).

Results

As compared to NC, HC had similar HBP, blood and urine concentrations of electrolytes (Na, K, Cl, tCO2 Mg, Ca), and values of PTH, vitamin D, renin, aldosterone and markers of bone remodeling as well as response to OGTT (all p>0.05, paired t test NC vs HC). Systolic BP increased similarly with age in both groups.
GS had renal hypokalemia, hypomagnesemia and low urinary calcium excretion. Ten patients had known hypertension. GS had however lower SBP than the other groups (mean difference 4.5 (CI95 1.18; 7.78), p 0.0087 and 4.1 mmHg (CI95 0.20; 8.07), p 0.0410; NN and HC vs GS) and higher cardiac frequency (mean difference 4.5 (CI95 -7.4; -1.5), p 0.0040 and -3.7 bpm (CI95 -7.0; -0.5), p 0.0271; NC and HC vs GS). The increase in SBP with age was blunted in GS patients. GS had significant higher basal glycaemia and insulin concentrations and HOMA-IR (homeostatic model assessment for insulin resistance) than the other groups independently of BMI. OGTT showed a prediabetes status in 14% of GS patients compared with 4 and 5% in HC and NC.

Conclusion

In conclusion, we found no difference between heterozygous carriers and age- and sex-paired healthy controls. GS patients have a risk to develop type 2 diabetes pointing out the importance of body weight control in GS patients.

Funding

  • Government Support - Non-U.S.