Which of the following is a common risk factor for developing Tetralogy of Fallot?

Maternal phenylketonuria (PKU) is indeed a common risk factor for the development of Tetralogy of Fallot (ToF). PKU is a genetic disorder that results in the inability to metabolize phenylalanine, leading to high levels of this amino acid in the blood. When pregnant mothers have untreated PKU, it can lead to various congenital heart defects in the fetus, including Tetralogy of Fallot. This link is particularly crucial as careful management of phenylalanine levels in pregnant women with PKU has been shown to significantly reduce the risk of such congenital anomalies.

In contrast, while maternal diabetes, hypertension, and drug abuse are associated with a range of congenital heart defects and other complications, they are not as specifically linked to the occurrence of Tetralogy of Fallot as maternal PKU. Maternal diabetes tends to be more linked to defects like transposition of the great arteries and congenital heart defects in general rather than ToF specifically. Similarly, maternal hypertension and drug abuse can lead to various adverse perinatal outcomes but do not have the same strong, direct correlation with ToF as seen with maternal PKU.