IGF2 and Silver-Russell syndrome: SRS patients can be divided into three subgroups based on their molecular etiology: maternal uniparental disomy of chromosome 7 (UPD(7)mat), loss of methylation on chromosome 11p15, (11p15 LOM; also known as hypomethylation of H19/IGF2:IG-DMR or H19 hypomethylation), and clinical SRS without any of these molecular findings.