However, new work details how KO of RBFOX2 orthologs in zebrafish (rbfox2 and rbfox1l) decrease the cardiac ventricular size, cause outflow tract hypoplasia, and decrease cardiomyocyte contractility [49], indicating both monogenic and polygenic variants may play a role in the etiology of HLHS. The gene discussed is RBFOX2; the disease is hypoplastic left heart syndrome.