Our Tests

Long QTS panel

Also known as: LQT syndrome, LQTS, Romano-Ward syndrome, Jervell Lange-Nielsen syndrome

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Purpose

Long QT syndrome (LQTS) can be an acquired or a familial disorder. The familial form of the disease is due to mutations in any one of at least 17 genes. A mutation in one copy of such a gene can cause an autosomal dominant mode of inheritance (Romano-Ward syndrome). LQTS can also be due to mutations in both copies of some of these genes, causing autosomal recessive LQTS (Jervell and Lange-Nielsen syndrome). The autosomal recessive form of the disease is associated with congenital deafness. The diagnosis of LQTS is made on the basis of clinical and electrocardiographic findings. Genetic testing is not necessary to make this diagnosis.

This test result has implications regarding the aetiology of LQTS in an individual, and the risk of LQTS and related disorders in a patient’s relatives.

This is an assay for heritable mutations. It may raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient.

This test can assist in making a diagnosis in an affected patient. It may also provide useful risk information for unaffected relatives. Testing unaffected people to provide risk information may require that the clinician comply with guidelines provided by professional and regulatory authorities regarding pre-test counselling and consent. In particular, national regulations stipulate that carrier testing of an unaffected child requires the laboratory to have evidence of pre-test counselling by a genetics professional and written consent. For advice or assistance, please contact us on 1800 010 447.

Clinical Utility

A pathogenic mutation can be found in approximately 70% of patients with a clinical diagnosis of LQTS. In an affected person with a clinical diagnosis of LQTS, the presence of a pathogenic mutation confirms the diagnosis of familial LQTS and may provide additional information regarding management and the risk of cardiac and non-cardiac manifestations in relatives. The identification of a mutation does not necessarily alter the management of the index patient. The absence of a pathogenic mutation in such a patient does not exclude the diagnosis of LQTS. In an unaffected person from a family with confirmed genetic diagnosis of LQTS, the presence of the family’s mutation may indicate an increased risk of developing LQTS, and close clinical follow-up may be warranted. The interpretation of such results depends on the particular gene and mutations. Pre-test genetic counselling is required.

Genes

This test involves analysis of a number of genes. Details of this gene panel and potential incidental findings are summarized where.

Test Method

Analysis of a gene panel for sequence abnormalities and deletions/duplications.

This test is provided by Bioscientia, a Sonic Healthcare laboratory in Germany. Bioscientia is accredited within Germany and by the College of American Pathology for the provision of medical genetic tests.

Test Ordering

This test is usually requested by a cardiologist with experience in the genetic management of cardiac disease or a clinical geneticist.

2-5 mL blood in EDTA. Specimens may be collected by the requesting practitioner or at any Sonic Healthcare pathology collection centre.

To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.

We also recommend that the patient or another adult check the labelling of request forms and sample tubes.

Special Instructions

Please include a statement about family history (or absence of family history) of the disease in clinical details on referral form. If family history is present, please state relationship to patient.

Price

$1,892

This is the price for initial genetic testing of an affected person. Once a family's mutation is identified, targeted mutation analysis can be offered to family members; please contact Sonic Genetics on 1800 010 447 or at info@sonicgenenetics.com.au regarding price and turn-around time.

Medicare Rebate

This test is not rebated by Medicare. The laboratory assumes that the patient or client has provided informed financial consent for the test.

Turnaround Time

6 weeks

Other Information

Heart Foundation