The investigators will identify high-impact rare genetic variants using whole exome sequencing in two patient groups: 1) women using BPs for OP and have had one or more AFF, 2) women using BPs for OP but have not had an AFF. The investigators will focus on genes/proteins that: i) regulate pyrophosphate/phosphate effects, ii) others that regulate BP metabolism, and iii) have been associated with OP. The investigators will use gene burden analysis to determine whether there is an excess of novel or rare genetic variants for the group with AFFs.