Subjects who have decline in TBBMC z-score of >0.5 from baseline at the one year on-treatment DXA will be discontinued from study and referred for additional clinical evaluation by the treating physician. In addition, if low impact or repeated fractures occur, a clinical evaluation by the treating physician, safety officer and Study PI will determine if the subject should remain on study.Monitoring DXA scan results of study subjects will be performed by Dr. Horlick, a Co-Investigator and Director of the Pediatric Body Composition Laboratory at St. Luke's-Roosevelt.