Among etiologic categories of CHD phenotypes, we detected a statistically significant synergistic effect between non-FAS and viral infection for conotruncal defects (RERI = 23.05, AP = 0.65, S = 3), RVOTO (RERI = 8.75, AP = 0.68, S = 3.77), and other specified CHDs (RERI = 1.54, AP = 0.41, S = 2.26). This evidence concerns the gene FAS and viral infectious disease.