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Congenital cardiac disease and inbreeding: specific defects escape higher risk due to parental consanguinity
Ghassan Chehab1, Philippe Chedid, Zakhia Saliba
1Department of Paediatrics, Lebanese University, Faculty of Medical Sciences, Hadath, Greater Beirut, Lebanon.
Insights
Parental consanguinity is higher in certain congenital heart defects, like tetralogy of Fallot. However, other heart conditions show no increased risk, suggesting different genetic causes for congenital heart disease.
Area of Science:
- Cardiovascular Genetics
- Developmental Biology
- Public Health
Background:
- Congenital heart defects (CHDs) are common birth defects with diverse etiologies.
- Parental consanguinity, a measure of genetic relatedness, is a known risk factor for some genetic disorders.
- Understanding the role of consanguinity in specific CHDs can elucidate underlying genetic mechanisms.
Purpose of the Study:
- To investigate whether the rate of parental consanguinity differs across various types of non-syndromic congenital heart defects.
- To identify specific CHDs associated with increased parental consanguinity.
Main Methods:
- A large cohort of 1585 newly diagnosed non-syndromic CHDs was compared to a control group of 1979 unaffected individuals.
- Statistical analyses, including Chi-squared tests and risk ratios, were employed.
- Consanguinity rates were assessed for first-degree cousins, first plus second-degree cousins, and any degree of consanguinity.
Main Results:
- Overall parental consanguinity was significantly higher in the CHD cohort (27.4%) compared to controls (23.9%).
- Specific CHDs, including tetralogy of Fallot, valvar aortic stenosis, and atrial septal defect, showed significantly higher parental consanguinity.
- Atrioventricular septal defects and discordant ventriculo-arterial connections did not show increased parental consanguinity.
Conclusions:
- The association between parental consanguinity and CHDs is specific to certain defect types.
- CHDs lacking an increased consanguinity risk may be influenced by X-linked or autosomal dominant genetic factors.
- These findings aid in understanding the genetic heterogeneity of congenital heart disease.
Aims:
To test on a large cohort whether parental consanguinity varies among different types of congenitally malformed hearts.
Methods And Results:
Between 1 May, 1999, and 28 February, 2006, a large cohort of 1585 newly diagnosed cases with non-syndromic congenitally malformed heart was enrolled at the National Register of Paediatric and Congenital Heart Disease, Lebanese Society of Cardiology, Beirut. Another group, made up of 1979 cases referred to the National Register of Paediatric and Congenital Heart Disease, but free of any malformation, and with a rate of consanguinity similar to a recent survey made by UNICEF in Lebanon, was used for the purposes of control. We used the Chi-squared test, and ratio of risk, to compare the groups. Subgroups with first degree cousins, first plus second degree cousins, and any degree of consanguinity, are significantly larger in the cohort with congenitally malformed hearts than in the control cohort, with proportions of 19.4%, 25.7%, and 27.4% versus 14.4%, 20.3%, and 23.9%, respectively. Those with tetralogy of Fallot, valvar aortic stenosis, and atrial septal defect have a significantly higher percentage of consanguineous parents than do the controls. By contrast, this is not the case for those with atrioventricular septal defect and common atrioventricular junction ("atrioventricular canal"), or discordant ventriculo-arterial connections ("transposition"). These differences persist when the types of congenital cardiac defect types are pooled according to presumed embryological processes. Those with hypoplasia of the left heart have increased parental consanguinity, but not the group of various types of discordant ventriculo-arterial connections.
Conclusion:
Only some types of congenitally malformed hearts have an increased percentage of parental consanguinity, suggesting that those types with no increased risk due to parental consanguinity are determined by genetic factors that are X-linked or exclusively autosomal dominant.
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