Orthotopic Heart Transplantation in a Patient With Gitelman Syndrome and Dilated Cardiomyopathy.

Gitelman syndrome (GS) is a rare hereditary tubulopathy affecting the distal tubule leading to significant electrolyte disturbances.1 Although generally a benign condition, rare associations with arrhythmias and sudden cardiac death have been reported.1 A paucity of literature exists associating GS with cardiomyopathy. We present a child with dilated cardiomyopathy and GS who was successfully treated with orthotopic heart transplantation.

Ventricular arrhythmia and tachycardia-induced cardiomyopathy in Gitelman syndrome, hypokalaemia is not the only culpable.

Gitelman syndrome (GS) is an autosomal recessive tubulopathy recently implicated in cases with ventricular arrhythmias (VAs), the latter being considered linked to electrolytes' imbalance. However, a direct causal relationship is considered to be an oversimplification for a complex molecular dysfunction. Recent work has suggested a degree of microvascular dysfunction in patients with GS that might be attributed as a mechanism of arrhythmia. We report a case of GS presenting with VAs complicated by cardiomyopathy. The high load of premature ventricular contractions that were attributed to the hypokalaemia has masked the presence of the left ventricular (LV) outflow tract tachycardia. Her LV systolic function recovered after successful electrophysiology ablation procedure. Atrioventricular nodal re-entry tachycardia was discovered incidentally during the study and was ablated successfully.

Acquired Gitelman's syndrome: an oxymoron?

We present the case of a 27-year-old woman with end stage renal disease from Diabetes Mellitus type 1 who had been on hemodialysis for a year. Her father, who was otherwise healthy, was evaluated as a possible living donor. Incidentally, during the workup process, he was identified as having Gitelman's syndrome (GS). The transplant proceeded without any complications, following which the recipient developed biochemical abnormalities consistent with GS. Both donor and recipient are doing well at this time. To our knowledge, this is the only known case of kidney donation by a patient with GS either living or deceased.

Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis (FHHNC): compound heterozygous mutation in the claudin 16 (CLDN16) gene.

BACKGROUND: Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis (FHHNC) is an autosomal recessive disorder of renal calcium and magnesium wasting frequently complicated by progressive chronic renal failure in childhood or adolescence. METHODS: A 7 year old boy was investigated following the findings of marked renal insufficiency and nephrocalcinosis in his 18-month old sister. He too was found to have extensive nephrocalcinosis with increased fractional excretion of magnesium: 12.4% (<4%) and hypercalciuria: 5.7 mmol (< 2.5/24 hours). He had renal impairment, partial distal renal tubular acidosis and defective urinary concentrating ability. Therapy with thiazide diuretics and magnesium supplements failed to halt the progression of the disorder. Both children subsequently underwent renal transplantation. Both children's parents are unaffected and there is one unaffected sibling. RESULTS: Mutation analysis revealed 2 heterozygous mutations in the claudin 16 gene (CLDN16) in both affected siblings; one missense mutation in exon 4: C646T which results in an amino acid change Arg216Cys in the second extracellular loop of CLDN16 and loss of function of the protein and a donor splice site mutation which changes intron 4 consensus splice site from 'GT' to 'TT' resulting in decreased splice efficiency and the formation of a truncated protein with loss of 64 amino acids in the second extracellular loop. CONCLUSION: The mutations in CLDN16 in this kindred affect the second extra-cellular loop of claudin 16. The clinical course and molecular findings suggest complete loss of function of the protein in the 2 affected cases and highlight the case for molecular diagnosis in individuals with FHHNC.