Heterozygous mutations in the human transcription factor gene NKX2.5 are associated with either isolated or combined congenital heart disease (CHD), primarily secundum atrial septal defect-II (ASD-II), ventricular septal defect (VSD) or tetralogy of Fallot (TOF). Thus, NKX2.5 has an important role at different stages of cardiac development. The frequency of NKX2.5 mutations in a broader phenotypic spectrum of CHD is not completely determined. Here, we report the identification of two novel mutations in the NKX2.5 gene in a screening of 121 patients with a broad spectrum of CHDs. However, mutations were only associated with familial ASD-II and in both, patients also showed atrioventricular (AV) block. We found one missense mutation (R190L) in two siblings with ASD-II and a frame-shift mutation (A255fsX38) at the C-terminus in a mother and daughter. In addition, a single patient with hypoplastic left heart syndrome (HLHS) had the reported sequence variant R25C. Importantly, sporadic cases of CHD that share phenotypic aspects of NKX2.5 mutation carriers were negative for genetic analysis. Thus, even important for cardiac development, germline mutations in NKX2.5 are rare in patients with sporadic CHD and genetic and/or pathophysiologic heterogeneity is likely for sporadic forms of CHD.

Intrathoracic ventricular aneurysms and diverticula can be differentiated by several criteria. Contractility is the only reliable parameter: aneurysms expand, whereas diverticula contract during ventricular systole.

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The genetic alterations leading to congenital heart defects (CHD) are still poorly understood. We and others have recently shown that in mice loss of Hey2 results in a high incidence of fatal ventricular and atrial septal defects, combined with tricuspid stenosis or atresia in some cases. The phenotype has been postulated to resemble human tetralogy of Fallot. Our analysis of CD1 outbred mice suggests that phenotypic consequences of Hey2 loss can be quite variable and dependent on modifier genes as we detected only isolated VSDs with lower prevalence and a significantly reduced mortality rate in this strain. Since Hey2 is one of the few Notch target genes, it is also conceivable that HEY2 mutations may account for cases of Alagille syndrome (AGS: variable combinations of heart, skeleton, eye, and facial malformations and cholestasis), in which the typical mutations of the Notch ligand JAG1 cannot be found. To clarify the role of HEY2 in human CHD and AGS, we screened by direct sequencing 23 children with CHD and 38 patients diagnosed with AGS, which lack mutations in the JAG1 gene. We found two types of silent changes in the coding region: a CTT-->CTG transition in exon 3 and a CTG-->CTC polymorphism in exon 5. Furthermore, a heterozygous SNP in the splice donor site of exon 4 was detected that is unlikely to disrupt splicing. Although the high incidence and variability of human congenital heart defects implies a multifactorial genetic basis, our results suggest that mutation of HEY2 is not a major contributing factor.

Hypoplastic left heart syndrome (HLHS) is a challenge for the pediatric cardiologist and the surgeon. It is generally assumed that the postoperative outcome after surgery for congenital heart disease is influenced by the institutional size. We present the results of 43 patients with true HLHS (situs solitus and atrioventricular and ventriculoarterial concordance) referred for operation between 1992 and 2002 in our center. Two children had atrioseptostomy: one died soon after the operation, and the other one was transplanted successfully but died at the age of 6 months following acute rejection. The remaining 41 underwent Norwood I palliation, 21 stage II palliation, and 10 stage III palliation. Early mortality was 29% after stage I operation, 4.7% after stage II palliation, and 0% after stage III operation. Overall mortality was 39% after stage I, 9.5% after stage II, and 10% after stage III operation. Low birth weight was associated with a higher mortality (p < 0.05). Mortality declined with increasing experience, comparable to the results of very large cardiosurgical centers with many more patients. The quality of surgery and perioperative management in smaller pediatric cardiosurgical centers can reach the level of very large centers.