After identification of a novel FREM1 deletion in a female infant with isolated left-sided CDH and a membranous sac, Beck et al. (127) developed a Frem1-deficient mouse model that displays a comparable phenotype with retrosternal diaphragmatic defect and reduced levels of cell proliferation in the anterior portion of the growing diaphragm, hereby showing that a deficit of FREM1 can lead to CDH in both humans and mice. The gene discussed is FREM1; the disease is congenital diaphragmatic hernia.