SSR2 and Hutchinson-Gilford progeria syndrome: We have previously developed a transgenic mouse model of HGPS by using a 164Kb circular BAC containing 4 functional genes (UBQLN4, RAB25, MEX3A, and a recombineered LMNA) in addition to incomplete sequences of two additional genes, SSR2 and SEMA4A (Varga et al., 2006).