There was no significant difference between patients with an NT-proBNP measurement at baseline and those without regarding age (p = 0.090), sex (p = 0.429), type of congenital heart defect (p = 0.436), presence of Down syndrome (p = 0.987), follow-up duration (p = 0.182), or mortality (p = 0.510). The gene discussed is NPPB; the disease is Down syndrome.