Conotruncal heart malformations are a group of cardiovascular defects resulting from abnormal cardiac outflow tract. The defects include: truncus arteriosus, tetralogy of Fallot, interrupted aortic arch, double outlet right (or left) ventricle, and transposition of the arteries.
Conotruncal heart malformations are associated with mutations in NKX2-6, NKX2-5, GATA6 and human chromosomal region 22q11. In some cases, conotruncal defects have also been observed as a component of DiGeorge, velocardiofacial, and other syndromes.
Abushaban et al. (2003) reported six cases of truncus arteriosus in four related families. Parents of all the affected children were consanguineous. Consanguinity combined with high incidence of truncus arteriosus in these families and normal karyotypes of the affected children led Abushaban et al. to suggest that the disorder could be monogenic, following Mendelian inheritance pattern.
Bhuiyan et al. (2014) reported two sisters with conotruncal heart malformations - one of them had tetralogy of fallot and the other sister had truncus arteriosus. Two KCNH2 gene mutations[p.Val172Met and p.Arg293Cys] were detected in both these patients as well as in two of their unaffected family members. Bhuiyan et al. conducted further investigations to study the effects of KCNH2 mutations on arrhythmia susceptibility in patients with conotruncal heart malformations and observed no significant impact.
In a study conducted by Al Talabani et al. (1998) to understand the pattern of major congenital malformations in 24,233 consecutive live and stillbirth at Corniche hospital, between January 1992 and January 1995, one case of conotruncal heart malformations was observed in a family from the United Arab Emirates. Recurrence was not reported in the family.