If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. [dovemed.com]

and in some cases, due to treatment also. [dovemed.com]

(Outcomes/Resolutions) The prognosis of Duodenal Atresia Tetralogy of Fallot is dependent upon the severity of the signs and symptoms and associated complications, if any Individuals with mild conditions have better prognosis than those with severe symptoms [dovemed.com]

(Etiology) The gene mutations causing Duodenal Atresia Tetralogy of Fallot have not been identified yet The disorder is transmitted in an autosomal dominant (with variable expression and reduced penetrance) or autosomal recessive manner Autosomal dominant [dovemed.com]

Tetralogy of Fallot: A population-based study of epidemiology, associated malformations and survival in Western Denmark 1984-1992. Scandinavian Cardiovascular Journal, 33(1), 45-48. Fairbanks, T. J., Kanard, R., Del Moral, P. M., Sala, F. [dovemed.com]