Similar skeletal fragility in conjunction with normal or even increased BMD has been described in several other instances in OI or monogenic osteoporosis.(60, 61) Also, similar phenotypic variability has been observed in other forms of monogenic osteoporosis, including osteoporosis related to WNT1.(62) This could partly be accounted for by interplaying lifestyle and environmental factors, as well as possible other genetic factors modifying the surfacing phenotype. Here, WNT1 is linked to osteoporosis.