The term 'atrioventricular septal defect' (AVSD) covers a spectrum of congenital heart malformations characterized by a common atrioventricular junction coexisting with deficient atrioventricular septation. In ostium primum atrial septal defect (ASD) there are separate atrioventricular valvar orifices despite ... The term 'atrioventricular septal defect' (AVSD) covers a spectrum of congenital heart malformations characterized by a common atrioventricular junction coexisting with deficient atrioventricular septation. In ostium primum atrial septal defect (ASD) there are separate atrioventricular valvar orifices despite a common junction, whereas in complete AVSD the valve itself is also shared (summary by Craig, 2006). AVSD, also designated endocardial cushion defect or atrioventricular canal defect (AVCD), is known to occur in either a nonsyndromic (isolated) form or, more commonly, as part of a malformation syndrome. The 2 syndromes most frequently associated with AVSD are Down syndrome (190685), in which AVSD is the most frequent congenital heart defect, and Ivemark syndrome (208530) (summary by Carmi et al., 1992). For a discussion of genetic heterogeneity of atrioventricular septal defects, see AVSD1 (606215).
Rajagopal et al. (2007) analyzed the GATA4 gene (600576) in 107 patients with congenital heart defects in the spectrum of Gata4-mutant mice and identified heterozygous missense mutations in 4 patients, including 2 (4.8%) of 43 patients with endocardial ... Rajagopal et al. (2007) analyzed the GATA4 gene (600576) in 107 patients with congenital heart defects in the spectrum of Gata4-mutant mice and identified heterozygous missense mutations in 4 patients, including 2 (4.8%) of 43 patients with endocardial cushion defects (600576.0007; 600576.0008). Both patients had a primum atrial septal defect and cleft mitral valve, and both had a reportedly unaffected parent who also carried the mutation. Zhang et al. (2008) screened 486 Han Chinese pediatric patients with congenital heart defects for mutations in the GATA4 gene, and identified heterozygosity for the previously identified P163S mutation (600576.0007) in a 1-year-old girl with a Rastelli type A endocardial cushion defect.