Activating calcium-sensing receptor gene variants in China: a case report of hypocalcaemia and literature review.

OBJECTIVES: Autosomal dominant hypocalcaemia 1 (ADH1) is a rare autosomal dominant genetic disease, due to the activating mutations of the calcium-sensing receptor ( CASR ) gene. The current paper presents a severe case of ADH1 with intellectual backwardness, and systematically reviews the reported 17 ADH1 patients in China.

CASE PRESENTATION: A 7 years old boy with recurrent seizures over 1 year was admitted at Yuying children' hospital, the clinical centre of south province of Zhejiang. Auxiliary examinations demonstrated hypocalcaemia, hyperphosphatemia, hypomagnesemia, hypercalciuria, low parathyroid hormone (PTH), basal ganglia calcifications, normal range of serum creatinine, and 25-hydroxyvitamin D. Wechsler's intelligence test result indicated intellectually backward. The patient's genotype found a heterozygous variant in CASR gene, c.T416C p. (Ile139Thr). This article also systematically reviews the literatures on ADH1 in China and summarises the clinical characteristics and treatment.

CONCLUSIONS: ADH1 can be a cause of idiopathic hypoparathyroidism. Recognition and rational treatment is important for symptom improvement and reducing high potential adverse effects.