目的　探讨家族性低镁血症高钙尿症和肾钙质沉着症（FHHNC）的临床特征和致病基因特点。方法　分析1 例2月龄FHHNC女性患儿的临床资料。结果　患儿血镁低，尿钙高；肾脏超声提示肾髓质回声增强；多次尿培养大肠埃 希菌。基因测序显示患儿CLDN16基因2处杂合变异c.324+1G>C，c.317C>T（p.Ser 106 Phe）。 予抗感染及25%硫酸镁、 门冬氨酸钾镁、10%枸橼酸钠口服治疗，病情好转。结论　FHHNC罕见且预后差，目前除肾移植外无特殊治疗方法，基因 检测有助于早期诊断。

Objective　Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is an autosomal recessive genetic disease caused by CLDN16 or CLDN19 gene mutation. This paper is aimed to discuss the clinical characteristics and disease—causing mutations in FHHNC. Methods　Clinical data of a patient with FHHNC was retrospectively analyzed. Results　A two months old patient with hypomagnesemia and nephrocalcinosis in bilateral kidneys was admitted. The child had low blood magnesium and high urinary calcium; renal ultrasound indicated enhanced renal medullary echo, with repeated positive results of the urine cultures of Escherichia coli. Gene sequencing showed two heterozygous variants c.324+1G>C, c.317C>T in the CLDN16 gene (p.Ser106Phe). It was clinically improved after being treated orally with anti-infection and 25% magnesium sulfate, potassium magnesium aspartate, and 10% sodium citrate. Conclusion　FHHNC is a rare disease with poor prognosis. At present, there is no special treatment except transplantation. Gene testing is helpful for early diagnosis of FHHNC.