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Pediatrics - Cardiology

Houston, Texas

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Pediatrics - Cardiology
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TGFBR2 Mutation Analysis

Transforming growth factor-beta receptor type 2 (TGFBR2), which is composed of seven exons and is located at 3p22, encodes a member of the serine/threonine protein kinase family and the TGF-beta receptor subfamily. The encoded protein is a transmembrane protein that has a protein kinase domain, forms a heterodimeric complex with type I TGF-beta receptor protein and binds TGF-beta.

Multiple mutations in TGFBR2 have been associated with Loeys-Dietz syndrome (LDS), which is characterized by hypertelorism, bifid uvula and/or cleft palate and generalized arterial tortuosity with ascending aortic aneurysm and dissection. Other findings in multiple systems included craniosynostosis, structural brain abnormalities, mental retardation, congenital heart disease and aneurysms with dissection throughout the arterial tree. Two types of LDS are distinguished: typical LDS (LDS type I) and probands presenting with vascular Elers-Danlos syndrome (LDS type II). TGFBR2 mutations have also been identified in patients with Marfan syndrome type II (MFS2) and familial thoracic aortic aneurysm 3 (AAT3/TAAD2). Mutations in TGFBR2 have been noted to demonstrate autosomal dominant inheritance with a variable clinical expression. Definitive genotype/phenotype correlations have not been described.

The John Welsh Cardiovascular Diagnostic Laboratory offers molecular genetic testing for TGFBR2 mutations. Individuals are tested by automatic fluorescent DNA sequencing of all 7 exons and 2 alternatively spliced exons 1A and 3A of the TGFBR2 gene. Genetic counseling is recommended for all individuals in order to identify additional at-risk family members and to discuss reproductive issues.

Reasons for Referral

Molecular confirmation of the diagnosis of Loeys-Dietz syndrome, Marfan syndrome type II, or familial thoracic aortic aneurysm 3.

Methodology

Genomic DNA is analyzed for TGFBR2 mutations by automatic fluorescent DNA sequencing of all seven exons and two alternatively spliced exons 1A and 3A of the TGFBR2 gene, as well as the exon/intron junctions and a portion of the 5′ and 3′ untranslated regions. Patient DNA is sequenced in both the forward and reverse orientations. If a mutation is identified, additional family members are analyzed only for the familial mutation(s) by automatic fluorescent DNA sequencing.

Service Fees

Service Direct and Institutional Billing CPT Codes
Index Case (Male or Female) $600 per sample 81405, G0452
Additional Family Members $300 per sample; known familial mutation only 81403, G0452

Sensitivity

DNA Sequencing Analysis: Approximately 95 percent detection of mutations in exons 1-7, 1A, and 3A of TGFBR2.

Specimen Requirements

Blood (preferred): EDTA (purple-top) tubes: Adult: 5 cc, Child: 5 cc, Infant: 2-3 cc
Tissue: Frozen (preferred), RNAlater, Formalin-fixed, Paraffin-embedded
Other Body Fluids: Call to inquire
Buccal Swabs: One swab from each cheek

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