In this observational study, we describe the phenotype of 33 patients carrying SMAD4 variants. Both hereditary haemorrhagic telangiectasia (HHT), a rare vascular genetic disease, and juvenile polyposis syndrome (JPS), a rare precancerous condition that confers an increased risk of developing gastrointestinal cancers, are known to be caused by SMAD4 pathogenic variants. Given SMAD4’s crucial role at the intersection of SMAD-dependent TGF-beta signaling pathways, we looked for symptoms of genetic connective tissue disorders in these patients. Such symptoms were observed in 61% of the patients in this study, thereby strengthening the proposed association. Based on our findings, we recommend screening all carriers of SMAD4 pathogenic variants for arterio-venous malformations, digestive polyps, aortic dilation, and skeletal complications. (By Dr Sophie Dupuis-Girod, https://jmg.bmj.com/content/early/2024/04/04/jmg-2023-109632 )