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Pediatrics - Cardiology

Houston, Texas

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Pediatrics - Cardiology
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KCNE2 Mutation Analysis

KCNE2 (potassium voltage-gated channel, Isk-related family, member 2), like KCNE1, is a member of the KCN family. The KCNE2 gene contains 1 exon spanning 7 kb of genomic distance that was mapped to chromosome 21q22.12. KCNE2 encodes the minK-related peptide (MiRP1), which has been linked to hereditary arrhythmias and pro-arrhythmic drug sensitivity. The MiRP1 regulates several ion channels, including a channel composed of proteins produced by the KCNH2 gene (4 alpha subunits form the structure of each channel) present in cardiac muscle, where they transport potassium ions out of cells. This form of ion transport is involved in recharging the cardiac muscle after each heartbeat to maintain a regular rhythm. Multiple mutations in KCNE2 have been linked to long QT syndrome type 6 (LQT6), Romano-Ward syndrome, and familial atrial fibrillation. KCNE2 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 KCNE2 mutations. Individuals are tested by automatic fluorescent DNA sequencing of the coding exons of the KCNE2 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 6 (LQT6), Romano-Ward syndrome, and familial atrial fibrillation.

Methodology

Genomic DNA is analyzed for KCNE2 mutations by automatic fluorescent DNA sequencing of the coding exons of the KCNE2 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) $600 per sample 81403, 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 exon of KCNE2.

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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