Unique genetic presentation of Gitelman syndrome in a Hispanic patient: Case report.

Abstract

Gitelman's syndrome, also known as, familial hypokalemia-hypomagnesemia, is a renal tubulopathy responsible for salt wasting resulting in, hypomagnesemia, hypocalciuria, and secondary activation of the renin-angiotensin-aldosterone system, responsible for the hypokalemia and metabolic alkalosis. Gitelman's syndrome is due to a rare, autosomal recessive gene mutation due to deletions, missense, nonsense, frame-shift, and splice-site mutation in the solute carrier family 12, member 3 gene. Solute carrier family 12, member 3, encodes a thiazide-sensitive sodium-chloride cotransporter in the apical membrane of cells within the distal convoluted tubule, leading to the development of Gitelman's syndrome. An 18-year-old male patient with a past medical history of chronic hypokalemia, hypomagnesemia, and constipation presented to the clinic as a continuation of care from his pediatric nephrologist for previously diagnosed Gitelman's syndrome in his childhood. Regarding his history of Gitelman's syndrome leading up to his diagnosis, at the age of 3, the patient was found to be hypokalemic on routine testing with no identifiable cause. The patient underwent genetic testing, where the test result demonstrated a positive solute carrier family 12, member 3 gene mutation, concurrent with Gitelman's syndrome. On genetic testing, heterozygous variants were also detected c. 179C>T, which is a known disease-causing mutation. Currently, the patient is being monitored due to persistent hydronephrosis of the bilateral kidneys. The patient has constantly dealt with hydronephrosis; however, kidney function has been preserved. The c.179C>T (Thr60Met) variant has been used to identify individuals with Gitelman's syndrome due to this mutation being the most common, thought to be found in 1-10/40,000 individuals, with higher prevalence within Asian demographics. Literature shows a greater association of Japanese and Chinese descent when compared to other demographic groups. This finding in an individual of Hispanic origin should increase suspicion that this finding can be found in individuals, not of Asian descent.