Gain-of-function mutations affecting the highly conserved 279th amino acid within analogous proliferating cell nuclear antigen (PCNA) domains of the CDKN1C gene have been reported in IMAGe syndrome and familial SRS (p.Arg279Pro, p.Arg279Ser, p.Arg279Leu) (15). The gene discussed is PCNA; the disease is Silver-Russell syndrome.