<b>Conclusion</b> In fetuses with DORV, TAC and TOF, the cardiac axis is significantly different from the normal axis, but in fetuses with TGA there is no significant difference compared to the normal axis.
In P2, we identified a novel nonsynonymous SNV in ZFPM2 (NM_012082.3:c.1576C>T), a known causative gene for TOF, which may act as a protective variant downstream of TBX1, haploinsufficiency of which is responsible for congenital heart disease in individuals with 22q11DS.
It is likely that hemizygosity of the TBX1 gene was causally related to TOF in this patient, although a synergistic pathogenic role of the JAG1 gene mutation in causing the heart defect cannot be excluded.
DiGeorge syndrome patients are haploinsufficient for Tbx1 and present a spectrum of conotruncal anomalies including tetralogy of Fallot, pulmonary atresia, and common arterial trunk.
Systematic survey of variants in TBX1 in non-syndromic tetralogy of Fallot identifies a novel 57 base pair deletion that reduces transcriptional activity but finds no evidence for association with common variants.
The deletion of chromosome 22q11 (del22q11) is a well established cause of DGS and VCFS, and it has been demonstrated also in sporadic or familial cases of TF.