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Background: The pathogenesis of transposition of the great arteries (TGA) is still largely unknown. In general, TGA is not associated with the more common genetic disorders nor with extracardiac anomalies, whereas it can be found in individuals with lateralisation defects, heterotaxy and asplenia syndrome (right isomerism)., Objective: To analyse genes previously associated with heterotaxy in order to assess mutations in familial TGA unassociated with other features of laterality defects., Methods: Probands of seven families with isolated TGA and a family history of concordant or discordant congenital heart disease were screened for mutations in the ZIC3, ACVR2B, LEFTYA, CFC1, NODAL, FOXH1, GDF1, CRELD1, GATA4 and NKX2.5 genes., Results: Mutation analysis allowed the identification of three sequence variations in two out of seven TGA probands. A FOXH1 (Pro21Ser) missense variant was found in a proband who was also heterozogous for an amino acid substitution (Gly17Cys) in the ZIC3 gene. This ZIC3 variant was also found in another family member with a second sequence variation (Val150Ile) in the NKX2.5 gene homeodomain who was affected by multiple ventricular septal defects. A second proband was found to harbour a splice site variant (IVS2-1G-->C) in the NODAL gene., Conclusions: The present study provides evidence that some cases of familial TGA are caused by mutations in laterality genes and therefore are part of the same disease spectrum of heterotaxy syndrome, and argues for an oligogenic or complex mode of inheritance in these pedigrees.

Objective: To review the outcome of patients with pulmonary atresia with intact ventricular septum after interventional perforation of the pulmonary valve, to assess the capability of this procedure to avoid neonatal or late intervention and to obtain a long-term biventricular repair., Design: Retrospective interventional study and clinical follow-up study., Setting: Tertiary referral centre., Patient Population: Between November 1994 and December 2007, 40 neonates underwent radiofrequency perforation. Median age at pulmonary valvotomy was 28 hours (range 1-147 hours) and median weight was 2925 g (range 1900-4400 g)., Main Outcome Measures: Procedural success and complication rates; early-term and long-term follow-up results., Results: The procedure was successful in 39 patients but 16 of them needed neonatal surgery. The overall mortality was 7.5%. At a median follow-up of 82 months, four patients underwent a bidirectional Glenn procedure, whereas all the other patients achieved a biventricular circulation without any further intervention in 19 of them. Patients who died or needed additional intervention with or without biventricular circulation failure had a higher incidence of bipartite right ventricular (65% vs 15.8% of those not needing additional intervention; p = 0.004) and a lower median tricuspid Z value (-2 (range -3.5 to 1) vs -0.5 (range -2 to 1); p = 0.004))., Conclusions: The results confirm that percutaneous interventional perforation is an effective first-stage procedure in patients with pulmonary atresia with intact ventricular septum. The right heart appeared to be adequate to maintain a long-term biventricular circulation in the large majority of cases.