目的　探讨恶性幼儿型石骨症的临床特点和基因特征。方法　分析1 例恶性幼儿型石骨症的临床资料和基因检测结果，并复习相关文献。结果　女性患儿，1 岁6 个月，X 线摄片显示全身骨骼密度增高硬化、骨髓腔缩小，脊椎椎体上下密度高、中间密度低。基因检测结果显示父亲及母亲TCIRG1基因11 号外显子出现杂合突变c.1450_1451insTc.1451A>T：484P>P，患儿为纯合突变；另外，骨骼发育异常的17 个相关基因COL9A1 出现一个错义突变，c.902C>T,p.Pro301Leu。结论　恶性幼儿型石骨症的诊断主要通过临床和基因检测。

　Objective　To study the clinical and genetic features of infantile malignant osteopetrosis. Methods　The clinical data and genetic testing results from one patient of infantile malignant osteopetrosis were analyzed. The related literatures were reviewed. Results　One year and six months old female, whose X-ray radiography showed generalize increased bone mineral density and reduced bone marrow space. The bone density was high in vertebral endplates and low in vertebral intermediate. Genetic testing showed that the heterozygous mutations of C.1450_1451insT c.1451A>T: 484P>P in TCIRG1 gene exon 11 in patient`s father and mother. The patient was homozygous mutation. In addition, a missense mutation c.902C>T, p. Pro301Leu of COL9A1 gene was found in the patient. Conclusion　The diagnosis of infantile malignant osteopetrosis is mainly according to clinical manifestations and genetic testing.