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Pediatrics - Cardiology

Houston, Texas

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Pediatrics - Cardiology
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SNTA1 Mutation Analysis

SNTA1 (syntrophin, alpha 1) is a member of the syntrophin gene family, which contains at least two other structurally-related genes. SNTA1 gene contains eight exons spanning 35.9 kb of genomic distance that was mapped to chromosome 20q11.2. Human SNTA1 encodes a deduced 505-amino acid peripheral membrane protein associated with dystrophin and dystrophin-related proteins, which is missing in patients with Duchenne Muscular Dystrophy and is present in reduced amounts in patients with Becker Muscular Dystrophy. Multiple mutations in SNTA1 have been identified in patients with long-QT syndrome type 12 (LQT12). SNTA1 mutations demonstrate autosomal-dominant inheritance with a broad range of clinical severity both within and between families. Definitive genotype/phenotype correlations have not been described.

The John Welsh Cardiovascular Diagnostic Laboratory offers molecular genetic testing for SNTA1 mutations. Individuals are tested by automatic fluorescent DNA sequencing of the coding exons of the SNTA1 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 long-QT syndrome type 12 (LQT12).

Methodology

Genomic DNA is analyzed for SNTA1 mutations by automatic fluorescent DNA sequencing of the coding exons of the SNTA1 gene, as well as the exon/intron junctions and a portion of the 5' and 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) $750 per sample 81405, G0452
Additional Family Members $300 per sample; known familial mutation only 81403, G0452

Sensitivity

DNA Sequencing Analysis: Approximately 99 percent detection of mutations in the coding exons 1-8 of SNTA1

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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