ZMPSTE24 and restrictive dermopathy: The most severe progerias stem from mutations affecting lamin Aproduction, a filamentous protein of the nuclear lamina.Hutchinson-Gilford progeria syndrome (HGPS) patients are heterozygous for aLMNA gene mutation while Restrictive Dermopathy (RD) individualshave a homozygous deficiency in the processing protease Zmpste24.