| Summary: | We experienced a case of familial hypoparathyroidism with an autosomal dominant
pattern of transmission and performed molecular analysis of the calcium-sensing receptor
(CASR) gene. The patient was a female neonate, born by cesarean section at term because of
breech presentation. Her mother had been diagnosed with idiopathic hypoparathyroidism at
the age of 9 yr and had been receiving vitamin D treatment since then. At birth, the
patient’s serum calcium concentration was 8.4 mg/dl, but it fell to 4.0 mg/dl on the fifth
day after birth. Furthermore, her serum intact PTH level was inappropriately low, while
hyperphosphatemia and hypomagnesemia were found. She was diagnosed with familial
hypoparathyroidism, and was immediately started on oral administration of 1α(OH)D3 (0.1
µg/kg/day) and continuous intravenous infusion of 8.5% calcium gluconate. Additionally,
trichlormethiazide was administered because of elevated urinary calcium/creatinine (Ca/Cr)
ratio. Her serum calcium concentration gradually improved thereafter. In this case,
autosomal dominant hypocalcemia (ADH) due to abnormality in the CASR gene was clinically
suspected, but DNA sequencing analysis revealed no mutation of the CASR gene in either the
patient or her mother. This result suggests that the patient’s hypoparathyroidism may have
been caused by abnormality in a gene other than CASR.
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