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Pediatrics - Cardiology

Houston, Texas

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Pediatrics - Cardiology
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KCNK3 Mutation Analysis

The KCNK3 gene encodes a member of the potassium channel family that characterized by the presence of four transmembrane domains and two pore domains per subunit. The KCNK3 gene contains 2 exons and spans about 40.7 kb genomic distance that has been mapped to 2p23.3. The encoded protein KCNK3 (also known as TASK) is an outwardly rectifying channel component that is sensitive to changes in extracellular pH and is inhibited by extracellular acidification. It controls the resting membrane potential in human pulmonary artery smooth muscle cells (PASMCs), and renders these cells sensitive to a variety of vasoactive factors. Mutations in KCNK3 gene are associated with pulmonary arterial hypertension (PAH). Definitive genotype/phenotype correlations have not been described.

The John Welsh Cardiovascular Diagnostic Laboratory offers molecular genetic testing for KCNK3 mutations. Individuals are tested by automatic fluorescent DNA sequencing of the coding exons of the KCNK3 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 pulmonary arterial hypertension (PAH).

Methodology

Genomic DNA is analyzed for KCNK3 mutations by automatic fluorescent DNA sequencing of the coding exons of the KCNK3 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 81404, 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 1-2 of KCNK3.

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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