Sometimes. Microdeletion of chromosome 22q11 (digeorge syndrome) is a genetic abnormality that has been linked to tof and other forms of congenital heart defects. It also can occur with Down syndrome (trisomy 21), and in patients with no identified genetic abnormality. Heart defects occur in 0.8% of babies, but in 3-5% of those with 1st degree relatives with heart defects. There is a genetic predisposition.
Not typically. Most cases are isolated and sporadic. It accounts for 5-10% of all congenital heart defects. 15% of tof cases are part of known genetic syndromes (down, digeorge, alagille, phenylketonuria) or associations (charge/vacterl) and some are linked to poorly controlled preconceptional maternal diabetes mellitus. Recurrence risk: 2.5% with one prior affected child, 8% with two. Folic acid may prevent it!
Complex gene impact. Heart defects develop from multiple genetic and non gene factors. They are not inherited directly like eye color or blood type. The general risk ~.5% will increase for any family factor. Mom, dad or another sibling with any heart defect increases the general risk/pregnancy. Exposures to certain meds, alcohol, inherited syndromes count. A second defect if it occurs, may be more or less complex.