Novel SLC12A3 mutation in Gitelman syndrome

Gitelman syndrome (GS) is an autosomal recessive disease characterised by the presence of hypokalaemic metabolic alkalosis with hypomagnesaemia and hypocalciuria. The prevalence of this disease is 1-10/40 000. GS is usually associated with mild and non-specific symptoms and many patients are only diagnosed in adulthood. The disease is caused by mutations in the SLC12A3 gene. We present the case of a 49-year-old man referred to a nephrology appointment due to persistent hypokalaemia and hypomagnesaemia. Complementary evaluation revealed hypokalaemia, hypomagnesaemia, metabolic alkalosis, hyperreninaemia, increased chloride and sodium urinary excretion, and reduced urinary calcium excretion. Renal function, remainder serum and urinary ionogram, and renal ultrasound were normal. A diagnosis of GS was established and confirmed with genetic testing which revealed a novel mutation in SLC12A3 (c.1072del, p.(Ala358Profs*12)). This novel mutation extends the spectrum of known SLC12A3 gene mutations and further supports the allelic heterogeneity of GS.