SORBS2is a genetic factor contributing to cardiac malformation of 4q deletion syndrome

Chromosome 4q deletion is one of the most frequently detected genomic imbalance events in congenital heart disease (CHD) patients. However, a portion of CHD-associated 4q deletions do not include known CHD genes. Alignment of those 4q deletions defined a minimal overlapping region including only one gene- SORBS2 . Histological analysis of Sorbs2 -/- heart revealed atrial septal hypoplasia/aplasia or double atrial septum. Mechanistically, SORBS2 had a dual role in maintaining sarcomeric integrity of cardiomyocytes and specifying the fate of second heart field (SHF) progenitors through c-ABL/NOTCH/SHH axis. In a targeted sequencing of a panel of known and candidate CHD genes on 300 CHD cases, we found that rare SORBS2 variants were significantly enriched in CHD patients. Our findings indicate that SORBS2 is a regulator of cardiac development and its haploinsufficiency may contribute to cardiac phenotype of 4q deletion syndrome. The presence of double atrial septum in Sorbs2 -/- hearts reveals the first molecular etiology of this rare anomaly linked to paradoxical thromboembolism.