患儿男，日龄26 d，生后18 d起出现反复抽搐，实验室检查示严重低镁血症（0.07 mmol/L）及低钙血症（1.65 mmol/L）。全外显子组测序结果示患儿TRPM6基因存在c.5616G>A（p.Trp1872Ter）和外显子20~23缺失复合杂合致病性变异，其中前者来自父亲，后者来自母亲，且均未见文献报道。该患儿确诊为原发性肠性低镁血症，口服硫酸镁治疗后未再发抽搐。随访8年，仅表现为持续性低镁血症，余无异常。该病例提示，基因检测有助于明确诊断，早期补充镁剂可有效控制症状，并且可预防神经系统不可逆损伤。

A 26-day-old male infant presented with recurrent convulsions from 18 days of life. Laboratory investigations revealed severe hypomagnesemia (0.07 mmol/L) and hypocalcemia (1.65 mmol/L). Whole-exome sequencing was performed and identified compound heterozygous pathogenic variants in the TRPM6 gene, comprising c.5616G>A (p.Trp1872Ter) and a deletion of exons 20-23. The c.5616G>A variant was inherited from the father, and the exon 20-23 deletion was inherited from the mother; neither variant has been previously reported. Based on these findings, the diagnosis of primary hypomagnesemia with secondary hypocalcemia was confirmed. Oral magnesium sulfate supplementation was initiated, and no further convulsions occurred. At the 8-year follow-up, the patient exhibited persistent hypomagnesemia without other abnormalities. This case highlights that genetic testing helps confirm the diagnosis, and early magnesium supplementation effectively controls symptoms and prevents irreversible neurological impairment.