Functional research unveiled that Glu125*-mutant PRRX1 lost transcriptional activation on the promoters of SHOX2 and ISL1, two genes where variations have been discovered to result in AF and CHD (Blaschke et al., 2007; Hoffmann et al., 2016, 2019; Li et al., 2018; Ma et al., 2019; Wang et al., 2019; Wu et al., 2020). The gene discussed is ISL1; the disease is atrial fibrillation.