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Pediatrics - Cardiology

Houston, Texas

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Pediatrics - Cardiology
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TGFBR1 Mutation Analysis

TGF - Beta Recepton I/II Domain OrganizationTransforming growth factor-beta receptor type 1 (TGFBR1), which is composed of nine exons and is located at 9q33-q34, encodes a member of the serine/threonine protein kinase family and the TGF-beta receptor subfamily. The protein encoded by this gene forms a heteromeric complex with type II TGF-beta receptors when bound to TGF-beta, transducing the TGF-beta signal from the cell surface to the cytoplasm.

Multiple mutations in TGFBR1 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 include 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). TGFBR1 mutations have also been identified in patients with Furlong syndrome (FS), a marfanoid disorder with craniosynostosis type II and familial thoracic aortic aneurysm 5 (AAT5). Mutations in TGFBR1 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 TGFBR1 mutations. Individuals are tested by automatic fluorescent DNA sequencing of all 9 exons of the TGFBR1 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, Furlong syndrome, or familial thoracic aortic aneurysm 5

Methodology

Genomic DNA is analyzed for TGFBR1 mutations by automatic fluorescent DNA sequencing of all 9 exons of the TGFBR1 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 1-9 of TGFBR1.

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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