目的 探讨钼辅因子缺乏症的临床及遗传学特征。方法 回顾分析1例确诊钼辅因子缺乏症患儿的临床资 料。结果 女性患儿，6月龄，生后即出现喂养困难、抽搐，并逐渐出现小头畸形、痉挛型四肢瘫等。全外显子测序发现患 儿MOCS 2基因存在c. 473 T>G（p.Leu 158 *）和c. 472 _ 477 del（p.Leu 158 _Lys 159 del）复合杂合变异，分别遗传自父亲和母 亲。按照美国医学遗传学学会指南，c. 473 T>G为致病变异，c. 472 _ 477 del为可能致病变异。结论 患儿被确诊为MOCS 2 基因杂合变异所致的钼辅因子缺乏症。

Objective To explore the clinical and genetic features of molybdenum cofactor deficiency. Method The clinical data of molybdenum cofactor deficiency in a patient was retrospectively analyzed. Result A 6 -month-old girl was born with no abnormalities. However, she had feeding difficulties and convulsion immediately after birth, and gradually developed microcephaly and spastic tetraplegia, etc. Whole exome sequencing showed compound heterozygous variation of c. 473 T>G (p.Leu 158 *) and c. 472 _ 477 del (p.Leu 158 _Lys 159 del) in MOCS2 gene, which were inherited from her father and mother respectively. According to the ACMG guidelines, the c. 473 T>G variation was classified as pathogenic, while the c. 472 _ 477 del variation was classified as likely pathogenic. Conclusion The child was diagnosed with molybdenum cofactor deficiency caused by heterozygous variation in the MOCS 2 gene.