BACKGROUND : Atrioventricular septal defects ( AVSDs ) occur as clinical defects of several different syndromes , as autosomal dominant defects , and as sporadically occurring malformations .
O O B-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature O B-DiseaseOrPhenotypicFeature O O O O O O O O O O O B-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature O O O O O B-DiseaseOrPhenotypicFeature O