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Atrioventricular canal defect without Down syndrome: a heterogeneous malformation
M C Digilio1, B Marino, A Toscano
1Department of Pediatric Cardiology, Bambino Gesù Hospital, Rome, Italy.
Insights
Atrioventricular canal defects (AVCD) often occur with other conditions, even without Down syndrome. This study found specific genetic syndromes and cardiac anomalies are linked to distinct AVCD subtypes.
Area of Science:
- Cardiology
- Medical Genetics
- Pediatrics
Background:
- Atrioventricular canal defect (AVCD) is a congenital heart defect frequently linked with extracardiac anomalies.
- While associations with Down syndrome and heterotaxy are well-studied, less is known about genetic syndromes and cardiac malformations in AVCD patients without Down syndrome and with situs solitus.
Purpose of the Study:
- To review genetic and cardiologic characteristics of patients with non-Down AVCD and situs solitus.
- To analyze the prevalence of genetic syndromes and additional cardiac malformations in this specific patient group.
Main Methods:
- Literature review of genetic and cardiologic features in non-Down AVCD with situs solitus.
- Analysis of a series of 203 consecutive patients with AVCD and situs solitus.
Main Results:
- 65% of patients had non-syndromic AVCD, while 35% had non-Down syndromic AVCD.
- Chromosomal imbalances (3%), Mendelian syndromes (22%), and non-syndromic extracardiac anomalies (10%) were identified.
- Complete AVCD was more common in chromosomal imbalances and associated with left-sided obstructive lesions; syndromic patients had more additional cardiac anomalies.
Conclusions:
- AVCD exhibits significant variability in anatomy and causes, even in patients without Down syndrome or heterotaxy.
- Specific genetic conditions are associated with distinct anatomical subtypes of AVCD.
Abstract:
The atrioventricular canal defect (AVCD) is one of the congenital heart defects most frequently associated with extracardiac anomalies. The association of AVCD with Down syndrome and heterotaxy has been studied extensively. However, little information is available about the prevalence of genetic syndromes and additional cardiac malformations in patients with AVCD and visceroatrial situs solitus without Down syndrome. This paper reviews the genetic and cardiologic characteristics of patients with non-Down AVCD and situs solitus in the literature and our series of 203 consecutive patients. In our experience, 132 (65%) of the patients have nonsyndromic AVCD, while 71 (35%) have non-Down syndromic AVCD. Chromosomal imbalances were detected in 7 cases (3%), Mendelian syndromes or associations in 44 (22%), and extracardiac anomalies without an identifiable syndrome in 20 (10%). Deletion 8p is prevalent among those with chromosomal imbalances. Noonan, Ellis-van Creveld, oro-faciodigital, Smith-Lemli-Opitz syndromes and VACTERL cases are frequent among patients with recognizable or identifiable nonchromosomal conditions. Based on this analysis of the type of AVCD and prevalence of associated cardiac anomalies in the different groups of patients, we found that: 1) the complete form is prevalent in patients with chromosomal imbalances; 2) the complete form is more frequently associated with additional cardiac defects, mainly left side obstructive lesions; and 3) additional cardiac anomalies are prevalent in syndromic patients. In conclusion, AVCD is a congenital heart defect with great variability in the anatomic patterns and heterogeneity of causes also in the subset without Down syndrome and without heterotaxy. The peculiar anatomic subtypes of this cardiac defect are associated with specific genetic conditions.