Endocrine Abstracts

Back Ground: Familial hypocalciuric hypercalcemia (FHH) is a benin cause of hypercalcemia that is characterized by autosomal dominant inheritence with high penetrance. In most cases, FHH results from inactivating mutations in the CaSR, the phenotypic aspect is a mild to moderate hypercalcemia, inappropriately normal or high PTH levels and relative hypocalciuria.

Case report: We describe an atypical case of a 46 years old man who had clinical finding compatible with FHH but with unusual description: asymptomatic severe hypercalcemia up to 3.02 mmol/l, high PTH level up to 166 ng/l and a very low 24 hours calciuria: calcium-to-creatinine-clearance ratio 0.0013. First Genetic analysis revealed an unknown missense variant CASR gene sequence: c.1682G>A (p.Cys561Tyr).

Discussion: Severe hypercalcemia is unusual with FHH type 1, we describe an atypical presentation of FHH. To our knowledge, this CASR sequence variation has not previously reported in the literature. Nevertheless, this is still a provisional result, it will be completed and confirmed by a second genetic analysis on a PAXgene blood DNA Tube.

Conclusion: This CASR mutation will probably represent a novel pathogenic sequence variation causing a type 1 FHH with severe hypercalcemia.