Alagille syndrome inherited from a phenotypically normal mother with a mosaic 20p microdeletion

Abstract

We report an 18-month-old girl with Alagille syndrome, caused by a submicroscopic deletion of chromosome 20p, including the Jagged1 (JAG1) gene. FISH using a BAC probe containing JAG1 identified the deletion. Chromosomes were normal at the 550 band level. The deletion was inherited from her phenotypically normal mother who was found to have the deletion in 9/20 cells studied from peripheral blood. This is the first report of a JAG1 deletion inherited from an apparently unaffected mosaic parent.