LMNA and Hutchinson-Gilford progeria syndrome: Progerin, the common protein product in all of these mutations, is a permanently farnesylated, aberrant lamin A protein that acts as a dominant negative, accelerating senescence of cells that express it.3 The severity and rate of disease progression in HGPS is reflected at least in part by the abundance of progerin,4 which in turn reflects the consequence of the specific germline mutation on spliceosome recognition of the cryptic donor.