ESPE Abstracts

Introduction: The extracellular calcium-sensing receptor (CaSR) enables the parathyroid glands and other CaSR-expressing cells involved in calcium homeostasis to sense alterations in calcium serum concentrations. Mutations in the CASR gene may produce gain or loss in its activity. Activating mutations cause a hypocalcaemic syndrome of varying severity, as autosomal-dominant hypocalcaemia or Bartter’s syndrome.

Case report: We describe a 6 months infant who was admitted to undergo a corrective surgery for tetralogy of Fallot. His mother, and four other relatives, were diagnosed with hypoparathyroidism and receiving treatment with calcium and calcitriol). Physical examination did not show dysmorphic features neither other significant findings. Postoperative and follow-up care showed hypocalcemia (8 mg/dl), hyperphosphatemia (up to 8.5 mg/dl), persistent hypercalciuria (ratio Ca/Cr 0.63 mg/mg) and low serum PTH (7 pg/ml). The CASR gene study detected a pathogenic mutation in heterozygous (c2488a G>A) designated as probably pathogenic, It was also presented in his mother. Currently, the patient is treated with calcium carbonate and calcitriol.

Conclusions: The prevalence of autosomal dominant hypocalcemia is unknown and probably underdiagnosed. Recognition of patients with an activating mutation of the CaSR has great relevance in prognosis as they present special vulnerability to treatment with calcium and vitamin D, so it should be included in the differential diagnosis of hypocalcemia. We present a case associated with Tetralogy of Fallot, not previously described which makes more difficult the diagnosis because the orienting toward the Di George syndrome.