Av canal defect, can this cause down syndrome?

Other way around: Atrioventricular (av) canal defect is a relatively common congenital heart defect in children born with down syndrome. Down syndrome "causes" av canal defects, not the other way around. Av canal defect is a major congenital anomaly with the potential to cause severe symptoms. However, in most cases, av canal defect can be repaired. High levels of surgical skill is important for best outcomes.

Av canal down: no vice versa, Down syndrome patients are more likely to have AV canal defect.