TBX1 and Truncus arteriosus: Conversely, in three other cases, inheritance from an unaffected parent, due to incomplete penetrance, was observed: a TBX1 known heterozygous missense variant [42] in one foetus presenting with truncus arteriosus and interventricular defect, and an already reported NOTCH2 heterozygous missense variant [37] in two foetuses conceived by the same couple presenting with a complex heart malformation and increased NT.