Acquired Gitelman syndrome in a primary Sjögren syndrome patient with a SLC12A3 heterozygous mutation: A case report and literature review

Abstract

Acquired Gitelman's syndrome (GS) associated with Sjögren syndrome (SS) is rare. A 50-year-old woman was admitted to our department because of nausea, acratia and sicca complex. Laboratory tests after admission showed renal failure, hypokalaemia, metabolic alkalosis, hypomagnesaemia and hypocalciuria, all of which met the diagnostic criteria for GS. Diagnostic evaluation identified primary SS as the cause of the acquired GS. Light microscopy of the renal tissue from the patient showed severe membranoproliferative glomerunephritis and tubulointerstitial nephritis. Immunohistochemical staining of the renal tissue showed the absence of sodium-chloride co-transporter (NCCT) in distal convoluted tubules. Genetic analysis of chromosomal DNA extracted from the patient's peripheral blood showed SLC12A3 gene heterozygous mutation. The reported case was comprehensively analyzed on the basis of the clinical features, and laboratory, pathological and genetic test findings. The patient has achieved a complete remission after meticulous care and appropriate treatment.

Keywords: Gitelman's syndrome; SLC12A3 mutation; Sjögren syndrome; sodium-chloride cotransporter.

Figure 1

Immunohistochemical staining of the sodium‐chloride cotransporter (NCCT) in (B) renal tubules of the patient compared with (A) control tissue from the kidney of a normal person shows that NCCT in the distal convoluted tubules has less reactivity than control, which is consistent with the diagnosis of Gitelman syndrome.

Figure 2

Genome sequencing of all exon regions of SLC12A3. (A) Schematic diagram of the SLC12A3 gene, with some exons (numbered boxes) and introns (lines). (B). Genome sequencing revealed a heterozygous mutation in C545A, which causes a Thr to Lys substitution at position 180. No additional mutation was found.