Familial Hypocalciuric Hypercalcemia: Clinical Aspects and Evolution

Familial hypocalciuric hypercalcemia (FHH) is a rare disease (ORPHA#405, www.orpha.net) and most likely underdiagnosed, that clinicians should be aware of in the differential diagnosis of a hypercalcemia. Appropriate identification of the FHH has implications in treatment and also for the family, since it is an automosal-dominant disease, due to mostly a heterozygous loss-of-function mutation of the CASR (calcium-sensing receptor) gene, but also much less freqüent mutations of another two genes (AP2S1 and GNA11). In case of clinical and biochemical suspicion of FHH, a genetic evaluation is mandatory. Nevertheless, an important number of patients, the genetic study is negative. This observational study is intended to perform a descriptive review of cases with clinical and biochemical suspicion of FHH who underwent a genetic study in the usual clinical practice. Clinical, biochemical and radiological characteristics, treatment, follow-up and comorbidities of genotype-negative participants will be compared with genotype-positive cases.