NOTCH2 and osteoporosis: Acro-osteolysis is a representative characteristic of Hadju–Cheney syndrome (HCS; MIM102500), an autosomal dominant disease caused by mutations in the last exon of NOTCH2 leading to a truncated protein.[15,16] With features of progressive focal bone destruction and craniofacial anomalies, it often exhibits similar phenotypes with OPDSDs, thus acro-osteolysis, generalized osteoporosis, cystonephrosis, and genetic test are required in differing HCS from OPDSDs.[17–20] Our cases’ NOTCH2 mutations were checked.