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Pediatrics - Cardiology

Houston, Texas

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Pediatrics - Cardiology
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SCN5A Mutation Analysis

SCN5A, mapped to chromosome 3p21, is composed of 28 exons spanning approximately 80 kb genomic distance. SCN5A, a cardiac sodium channel gene, encodes a 2,016-amino acid protein that has a structure similar to that of previously characterized sodium channels and contains four homologous domains, each of which has six putative membrane-spanning regions. Multiple mutations in SCN5A have been identified in patients with Brugada syndrome, long QT syndrome-3 and idiopathic ventricular fibrillation. SCN5A mutations demonstrate autosomal dominant inheritance with a broad range of clinical severity both within and between families. Definitive genotype/phenotype correlations have not been established.

The John Welsh Cardiovascular Diagnostic Laboratory offers molecular genetic testing for SCN5A mutations. Individuals are tested by automatic fluorescent DNA sequencing of the coding exons of the SCN5A gene. We strongly recommend initial testing of a clearly affected individual, if available, in order to provide the greatest test sensitivity and clearest interpretation of results for subsequent family members. Genetic counseling is recommended for all individuals.

Reasons for Referral

Molecular confirmation of the diagnosis of Brugada syndrome, Long QT syndrome, and idiopathic ventricular fibrillation.

Methodology

Genomic DNA is analyzed for SCN5A mutations by automatic fluorescent DNA sequencing of all coding exons of the SCN5A gene, as well as the exon/intron junctions and a portion of the 3` untranslated region. 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 by automatic fluorescent DNA sequencing.

Service Fees

Service Direct and Institutional Billing CPT Codes
Index Case (Full Gene) $1100 per sample 81407, G0452
Additional Family Members $300 per sample; known familial mutation only 81403, G0452

Sensitivity

DNA Sequencing Analysis: Approximately 99 percent detection of mutations in coding exons of SCN5A.

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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