• Asma Deeb, Salima Atia Abood, Job Simon, Hormazdiar Dastoor, Simon Hs Pearce, and John A Sayer.
• Institute of Genetic Medicine, Newcastle University, International Centre for Life, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK. john.sayer@ncl.ac.uk.
• BMC Res Notes. 2013 Dec 10; 6: 527.

BackgroundFamilial hypomagnesaemia with hypercalciuria and nephrocalcinosis is a rare tubulopathy leading to renal calcification and progressive renal failure.Case PresentationWe report a consanguineous Arab family (of Qatari origin) with 7 affected siblings with variable phenotypes including hypomagnesaemia, hypercalciuria, nephrocalcinosis and renal stones. Presenting features included haematuria and recurrent urinary tract infections. As the biochemical and clinical phenotypes of this family resembled familial hypomagnesaemia with hypercalciuria and nephrocalcinosis, we performed genetic investigation in order to provide a precise molecular diagnosis. We screened all coding regions of the CLDN16 gene and identified a novel mutation (c.G647A, p.R216H) which was found homozygously in the six severely affected cases, who manifested significant nephrocalcinosis, often nephrolithiasis and sometimes reduced GFR. Parents were both heterozygous for the mutation and, together with children carrying the mutation in its heterozygous state, exhibited mild or no biochemical phenotypes.ConclusionMutations in CLDN16 underlie familial hypomagnesaemia with hypercalciuria and nephrocalcinosis but remain a rare cause of nephrocalcinosis and nephrolithiasis. Management includes reduction of hypercalciuria with thiazide diuretics, correction of serum magnesium and close monitoring of renal function given the significant risk of end stage renal failure with this inherited form of nephrocalcinosis.

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