CTNND1‐Related Disorder: New Insight on Prenatal Phenotype

: CTNND1 is a gene located in 11q12.1, encoding for p120 catenin, a protein involved in maintaining adherent junctions, regulating the epithelial-mesenchymal transition, and transcriptional signaling of different cellular pathways. Pathogenic variants in CTNND1 are classically associated with isolated cleft palate and Blefaro-cheilo-dontic syndrome, an autosomal dominant condition characterized by abnormalities of the eyelid. Considering different signs and symptoms associated first with Blefaro-cheilo-dontic syndrome and later specifically with CTNND1, Ahlaratani and colleagues proposed a wider developmental role for CTNND1 than previously described, associating a broader phenotypic spectrum. This report describes a prenatal case in which a CTNND1 pathogenic variant and reverse phenotyping allowed a diagnosis of Blefaro-cheilo-dontic syndrome associated with characteristics never related to Blefaro-cheilo-dontic syndrome or CTNND1, such as hydrocephalus. This report is the first detailed fetal case of Blefaro-cheilo-dontic syndrome, and the new feature reported is consistent with CTNND1 developmental role and may add new insights into the phenotype spectrum that is being defined.