International Clinical and Medical Case Reports Journal (ISSN: 2832-5788) | Volume 4, Issue 2 | Case Report | Open Access DOI
Muhammad Akram Khan*
Khan MA* , Yoo J , Rayapati LT , Zubedi MA, Khurram F, Sobi D, Ahsanullah ST
Department of Cardiology, Cardiac Center of Texas, Baylor Heart Hospital, Plano, TX, USA
*Correspondence to: Muhammad Akram Khan
Fulltext PDFBicuspid aortic valve (BAV) is a congenital heart defect characterized by the presence of two aortic valve leaflets instead of the usual three. This structural anomaly affects approximately 1-2% of the general population and is linked to various complications, such as aortic stenosis, dilation, and aneurysm formation, due to turbulent blood flow through the valve. BAV is frequently inherited, with studies suggesting an autosomal dominant pattern with incomplete penetrance, indicating that genetic predisposition alone does not guarantee its development. In fact, despite the hereditary basis of BAV, cases have emerged showing discordance in BAV phenotypes among monozygotic twins, including monochorionic twins, where concordance rates are estimated at around 20%. These findings suggest that, in addition to genetic factors, epigenetic and environmental influences during prenatal development may play crucial roles in BAV manifestation. This discordance among identical twins highlights the potential impact of intrauterine conditions, such as oxygen levels and other environmental exposures, that may influence the phenotypic expression of BAV.
We present a case of phenotypic discordance in identical 66- year-old male twins. The first twin was diagnosed with severe aortic stenosis and a BAV, accompanied by a thoracic aortic aneurysm. He underwent successful transcatheter aortic valve replacement (TAVR) and aortic grafting. His identical twin brother was identified to have aortic valve with no significant aortic abnormalities and only mild pulmonary artery dilatation.
The findings from this case study underscore the complexity of bicuspid aortic valve (BAV) inheritance, indicating an autosomal dominant pattern with incomplete penetrance. The discordance observed among identical twins highlights the significant roles of epigenetic and environmental factors in the manifestation of this condition. While genes such as NOTCH1, GATA5, and FBN1 are implicated in BAV, their expression may be modulated by various external conditions during development. Factors like maternal health, nutritional status, and exposure to environmental toxins can influence epigenetic modifications, resulting in differences in gene expression that affect cardiac morphology. Additionally, prenatal conditions unique to monochorionic twins, including twin-to-twin transfusion syndrome, can further complicate phenotypic expression. This interplay between genetic predispositions and environmental influences emphasizes the need for a comprehensive approach to understanding the etiology of BAV and other congenital heart defects.
This case emphasizes the need for further research into the genetic, environmental, and epigenetic factors influencing BAV development. Understanding these factors may improve genetic counseling, early diagnosis, and intervention strategies for BAV.
Environmental influences; Epigenetic Discordant; Identical twins; Bav; Case reports
Khan MA, Yoo J, Rayapati LT, Zubedi MA, Khurram F, Sobi D, et al. Identical Twins Discordant For Bicuspid Aortic. Int Clinc Med Case Rep Jour. 2025;4(2):1-20.