Fourth, while classification into HGPS, HGPS-like and atypical progeria syndrome (APS) is based on specific LMNA or ZMPSTE24 mutations, we were unable to directly quantify Progerin or farnesylated prelamin A levels in HGPS-like and APS patients due to limited availability of detection kits. This evidence concerns the gene ZMPSTE24 and autoimmune polyendocrinopathy.