CDH1-associated Blepharocheilodontic Syndrome Registry

Blepharocheilodontic Syndrome (BCDS) is a rare genetic disorder characterized by cleft lip and/or palate (CL/P), eyelid malformations, and features suggestive of ectodermal dysplasia. Variants in the CDH1 gene, which encodes the cell adhesion protein E-cadherin, have been implicated in BCDS. Functional studies have demonstrated that CDH1 plays a critical role in lip and palate development during embryogenesis (Ghoumid 2017; Figueiredo 2019).

In the hereditary cancer genetics community, CDH1 is more commonly associated with hereditary diffuse gastric and lobular breast cancer syndrome (DGLBC). CDH1 variants linked to DGLBC are typically truncating mutations, resulting in a null allele. In contrast, CDH1 variants observed in individuals with BCDS are often missense mutations located in the EC1-EC2 linker region (amino acids 254-257) or exon 9 donor splice site variants (e.g., c.1320G\>T, c.1320+1G\>A, c.1320+1G\>T, c.1320+1G\>C, c.1320+5G\>A) (Ghoumid 2017; Kievit 2018).

Historically, it was believed that individuals with BCDS-associated CDH1 missense variants were not at increased risk for DGLBC-associated cancers. This assumption was based on the absence of reported cancer cases in published BCDS families and epidemiological data from the CDH1 ClinGen Variant Curation Expert Panel (VCEP), which suggested that missense variants may not confer elevated cancer risk (Ghoumid 2017; Kievit 2018; Lee 2018).

However, a 2020 case report by LeBlanc et al. described a family with a known BCDS-associated CDH1 missense variant (c.768T\>A, p.N256K), in which a 37-year-old male developed diffuse gastric cancer. This report raised concerns about potential cancer risks in individuals with BCDS-associated CDH1 variants and prompted questions regarding the need for endoscopic screening and other surveillance measures.

Currently, data regarding cancer risk in individuals with CDH1 variants and the BCDS phenotype are limited. The condition is rare, and affected individuals are often identified through exome sequencing due to multiple congenital anomalies. The interpretation of familial cancer risk is further complicated by a high rate of de novo mutations and limited family history.

To address these gaps, this registry aims to establish a centralized, international cohort of individuals with CDH1-associated BCDS. The goal is to better characterize the genotype-phenotype correlations, define the clinical spectrum, and assess the potential cancer risks associated with these variants.

• Development of evidence-based cancer surveillance recommendations for individuals with CDH1-assocaited blepharocheilodontic syndrome. [Time frame: 10 years]