Congenital Diaphragmatic Hernia and Joint Laxity: A Putative Link with Heritable Connective Tissue Disorders

<b>Background/Objectives:</b> The etiology of congenital diaphragmatic hernia (CDH) remains unknown in over 50% of cases, although multiple heterogeneous causative defects have been identified. Emerging evidence suggests that specific genes and molecular pathways involved in connective tissue biology may contribute to CDH development. Associations between CDH and connective tissue disorders have been reported, including cases in Marfan syndrome and a prevalence of CDH in 34% of patients with arterial tortuosity syndrome. Noticing joint laxity in several CDH patients, we aimed to investigate the presence of genetic variants linked to connective tissue disorders in this subgroup, focusing on patients enrolled in the follow-up program at Bambino Gesù Children's Hospital. <b>Methods</b>: We selected patients diagnosed with CDH who also exhibited joint laxity based on a positive Beighton scale. These individuals underwent molecular analysis targeting genes known to be associated with heritable connective tissue disorders. <b>Results:</b> Genetic testing revealed variants in several genes across our patient series. These included mutations in <i>FBN1</i>, <i>FBN2</i>, <i>ZNF469</i>, <i>VEGFA</i>, <i>NOTCH1</i>, <i>ELN</i>, <i>MCTP2</i>, and <i>SMAD6</i>. In some cases, the variants were inherited paternally, while others appeared de novo. Most of these variants were classified as of unknown significance according to ACMG guidelines. <b>Conclusions:</b> (1) Several "variants of unknown significance" in different genes causative for connective tissue disorders have been detected in half of the present series of patients with CDH and joint laxity; (2) although the majority of the variants are classified accordingly to the ACMG as "variants of unknown significance", a role of predisposition or susceptibility to CDH cannot be excluded; (3) a precise clinical evaluation for features of connective disorders should be recommended in the diagnostic workflow of patients with CDH.