A Case of Familial CDKN1C-Related Beckwith-Wiedemann Syndrome.

We report a case of a male fetus born to an unrelated couple with a fetal phenotype of an omphalocele and inferior vermian hypoplasia. Prenatal trio exome sequencing identified a maternally inherited pathogenic CDKN1C variant consistent with Beckwith-Wiedemann syndrome (BWS). This finding prompted targeted testing of the proband's sibling, who was confirmed to carry the same variant. Posterior fossa abnormalities have been reported in cases with BWS, and specifically in children with the CDKN1C loss-of-function variant.