Paternal 132 bp deletion affecting <i>KCNQ1OT1</i> in 11p15.5 is associated with growth retardation but does not affect imprinting

Abstract

Microdeletions within the paternal IC2 affecting the <i>KCNQ1OT1</i> gene have been described in only five families, and they all include the differentially methylated region <i>KCNQ1OT1</i>:TSS-DMR/IC2 and parts of the <i>KCNQ1</i> gene. However, these deletions have different impacts on the expression of both genes and the cell-cycle inhibitor <i>CDKN1C</i>. They thereby cause different phenotypes. The 132 bp deletion is the smallest deletion in the IC2 reported so far. It does not affect the IC2 methylation in general and the coding sequence of the <i>KCNQ1</i> gene. Thus, the deletion is only associated with a growth retardation phenotype when paternally transmitted but not with other clinical features in case of maternal inheritance as observed for larger deletions.