SGMS2 and spondylometaphyseal dysplasia: The clinical presentations of SGMS2-related osteoporosis range from childhood-onset osteoporosis with low BMD and skeletal fragility with or without sclerotic doughnut-shaped lesions in the skull to a severe spondylometaphyseal dysplasia with neonatal fractures, long-bone deformities, and short stature (4–8, 26).