We find that functional dystroglycan glycosylation is important in muscle development differentiation and fiber maintenance, but that defects initiated at E8 expected to affect muscle development differentiation appear necessary to induce more severe disease with prevalent weakness and wasting does tamoxifen cause weight gain In a study of breast cancer patients undergoing treatment with tamoxifen, metabolic flare was observed in breast tumors and metastatic disease sites on positron emission tomography PET with glucose analog F 18 fluorodeoxyglucose FDG; an early increase in FDG uptake after 7 to 10 days of tamoxifen was predictive of ultimate response to tamoxifen 37