Management Approach for Variants of Uncertain Significance in FBN1, FBN2, and LTBP4 Genes
Understanding Variants of Uncertain Significance
- Variants of uncertain significance (VUS) in FBN1, FBN2, and LTBP4 genes represent genetic alterations where there is insufficient evidence to classify them as either pathogenic or benign, and the American Heart Association recommends comprehensive cardiovascular evaluation for these patients 3
- The FBN1 gene is associated with Marfan syndrome, an autosomal dominant connective tissue disorder that can lead to aortic dilatation, dissection, and rupture, according to the European Society of Cardiology 2, 1
- FBN2 variants are associated with congenital contractural arachnodactyly and other connective tissue disorders, as stated by the European Heart Journal 2
- LTBP4 variants have been linked to cutis laxa and connective tissue disorders, as reported by the American College of Medical Genetics 4
Clinical Evaluation Approach
- Patients with VUS in FBN1, FBN2, and LTBP4 genes should undergo comprehensive cardiovascular evaluation including echocardiography and clinical assessment for Marfan syndrome features, regardless of the uncertain genetic status, as recommended by the American College of Cardiology 1, 2
- The European Society of Cardiology recommends performing thorough cardiovascular evaluation with echocardiography to assess for aortic root dilatation, mitral valve prolapse, and other cardiac manifestations 1, 2
- Baseline echocardiography should be performed to measure aortic root dimensions, according to the American Heart Association 1
Management Strategy Based on Clinical Findings
- For patients with no clinical features, the European Heart Journal recommends baseline cardiovascular evaluation with echocardiography, and if normal, consider periodic cardiovascular monitoring (every 2-5 years) 2
- For patients with some clinical features, more frequent cardiovascular monitoring (every 1-2 years) is recommended by the American College of Cardiology, and consider activity restrictions based on clinical findings, not solely on genetic status 2, 1
- For patients with significant clinical features, management should follow guidelines for the suspected clinical syndrome regardless of VUS status, as stated by the American Heart Association 1
Genetic Counseling and Family Management
- The American College of Medical Genetics recommends explaining that VUS cannot be used for predictive testing in family members, and consider testing affected family members to help reclassify the variant 5
- Family segregation studies can provide valuable information for variant reclassification, according to the National Society of Genetic Counselors 5