<h4>Background</h4>Pathogenic variants in <i>KDM3B</i> have been implicated as the cause of Diets-Jongmans syndrome (DIJOS), an autosomal-dominant disorder characterized by growth retardation, intellectual disability, facial dysmorphism and autism-spectrum disorder. The gene discussed is KDM3B; the disease is Diets-Jongmans syndrome.