ECE1 and Abnormal cardiac septum morphology: Similarly, a heterozygous loss-of-function mutation in ECE1 (21,543,740–21,672,034; hg19) has been identified in an individual with patent ductus arteriosus, a small subaortic ventricular septal defect, and a small atrial septal defect, suggesting that haploinsufficiency of this proximal 1p36 gene may be sufficient to cause cardiovascular malformations in humans [10].