Atrial Septal Defect (ASD) With Atrioventricular Block (AVB): NKX2.5 (Full Gene Sequencing)

CPT: 81479
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Test Details

Test Includes

This test covers all coding nucleotides of gene NKX2.5, plus at least two and typically 20 flanking intronic nucleotides upstream and downstream of each coding exon, covering the conserved donor and acceptor splice sites, as well as typically 20 flanking nucleotides in the 5′ and 3′ UTR.

Use

Identify NKX2.5 mutations as the cause of familial ASD, indicating high risk of AVB and allowing early diagnosis in family members

Limitations

This method does not reliably detect mosaic variants; large deletions; large duplications, inversions, or other rearrangements; or deep intronic variants. It may be affected by allele-dropout, it may not allow determination of the exact numbers of T/A or microsatellite repeats, and it does not allow any conclusion as to whether two heterozygous variants are present on the same or on different chromosome copies.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

Methodology

DNA sequencing

Reference Interval

Normal equals reference sequence or variants that are known or predicted to be benign; abnormal equals all other variants.

Additional Information

Atrial septal defects (ASDs), which account for ~10% of all congenital heart disease, are characterized by an opening in the atrial septum that creates a connection between the systemic and pulmonary circulation, increasing the risk of strokes and, over time, leading to irreversible damage to heart and lungs. About 8% to 19% of familial ASDs are due to autosomal dominant mutations in the gene NKX2-5, which also predispose patients to a high risk of atrioventricular block (AVB) and attendant cardiac arrhythmias. Genetic testing can confirm a high risk of AVB in patients with ASD and allow for accurate identification of mutation carriers within affected families.

Specimen Requirements

Specimen

Whole blood; DNA is accepted (Call 866-647-0735 for DNA collection information.)

Volume

2 mL

Container

Lavender-top (EDTA) tube

Collection

Samples may be stored for brief periods at 4°C. Ship overnight at room temperature.

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Container broken or leaking; container not labeled or label not legible

Clinical Information

Special Instructions

In cases in which a known mutation can be documented, the physician may prefer to order test 252651.

Test orders must include an attestation that the provider has the patient's informed consent for genetic testing. See sample physician office consent form: Consent for Genetic Testing. In the case of family tests (ie, known mutations), Correlagen requires the result report of the first patient tested in the family (the index case), if not performed at Correlagen. Other family members are subsequently tested for the specific mutation found in the first patient tested.

References

Benson DW. Genetics of atrioventricular conduction disease in humans. Anat Rec A Discov Mol Cell Evol Biol. 2004 Oct; 280(2):934-939. 15372490
Webb G, Gatzoulis MA. Atrial septal defects in the adult: Recent progress and overview. Circulation. 2006 Oct 10; 114(15):1645-1653. 17030704

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
252405 ASD with AVB: NKX2.5 252059 Routing 41103-3
252405 ASD with AVB: NKX2.5 252402 ASD with AVB: NKX2.5 N/A

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The LOINC® codes are copyright © 1994-2017, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee. Permission is granted in perpetuity, without payment of license fees or royalties, to use, copy, or distribute the LOINC® codes for any commercial or non-commercial purpose, subject to the terms under the license agreement found at https://loinc.org/license/. Additional information regarding LOINC® codes can be found at LOINC.org, including the LOINC Manual, which can be downloaded at LOINC.org/downloads/files/LOINCManual.pdf