Leukocyte adhesion deficiency type III (LAD-III) is caused by mutations in FERMT3 that encodes Kindlin-3 which regulates integrins activation. LAD-III predisposes to infections and bleeding. Osteopetrosis was reported in some cases. We report three patients who presented as malignant infantile osteopetrosis. One had recurrent infections and none had bleeding. Exome sequencing revealed a novel homozygous mutation in FERMT3 c.1555C > T (p.Gln519Ter). Two patients underwent successful hematopoietic stem cell transplant (HSCT) from matched siblings with resolution of osteopetrosis. The third patient died secondary to sepsis prior to HSCT. Our results support early HSCT in LAD-III prior to the occurrence of life-threatening complications.

白细胞粘附缺陷型III（LAD-III）是由FERMT3中的突变引起的，该突变编码Kindlin-3，后者调节整联蛋白的激活。LAD-III易于感染和出血。在某些情况下有骨质疏松症的报道。我们报告了三例表现为恶性婴儿骨质疏松症的患者。一例反复感染，无一例出血。外显子组测序显示FERMT3 c.1555C> T（p.Gln519Ter）中有一个新的纯合突变。两名患者从相匹配的兄弟姐妹处成功完成了造血干细胞移植（HSCT），并获得了骨质疏松症的解决。第三例患者在HSCT之前死于败血症。我们的结果支持LAD-III早期HSCT在威胁生命的并发症发生之前。