LMNA and Hutchinson-Gilford progeria syndrome: To assess the effect of in vivo systemic progerin suppression and lamin A restoration starting at different stages of HGPS progression, we defined 2 ages for the start of tamoxifen administration, representing early disease (≈6 months: beginning of growth failure, one of the earliest symptoms in patients with HGPS) and late disease (≈13 months: close to maximum survival; Figure 7A, Table).