Corin and Left Atrial Cardiomyopathy, Hypertension, Arrhythmia, and Fibrosis

Two siblings presented with cardiomyopathy, hypertension, arrhythmia, and fibrosis of the left atrium. Each had a homozygous null variant in CORIN, the gene encoding atrial natriuretic peptide (ANP)-converting enzyme. A plasma sample obtained from one of the siblings had no detectable levels of corin or N-terminal pro-ANP but had elevated levels of B-type natriuretic peptide (BNP) and one of the two protein markers of fibrosis that we tested. These and other findings support the hypothesis that BNP cannot fully compensate for a lack of activation of the ANP pathway and that corin is critical to normal ANP activity, left atrial function, and cardiovascular homeostasis. Findings from a study involving two siblings homozygous for a null variant in CORIN have implications for understanding the extent to which the BNP and ANP pathways overlap.