Long QT Syndrome-Population Genetics and Cardiac Studies (LQTS)

October 20, 2015 updated by: Arthur J. Moss, University of Rochester
To investigate the clinical, genetic and cardiologic aspects of the Long QT Syndrome, a predominantly hereditary disease with episodic malignant arrhythmias and sudden death, and a demonstrated gene linkage in a large pedigree.

Study Overview

Detailed Description

BACKGROUND:

The Long QT Syndrome (LQTS) is an infrequently occurring disorder of unknown cause in which affected individuals have an unusual electrocardiographic repolarization abnormality and a propensity to syncope and fatal ventricular tachyarrhythmias. The first family with LQTS was described by Jervell and Lange-Nielsen in 1957. Three sudden deaths occurred in four deaf children with QT prolongation; two other children and the parents were healthy with normal hearing and normal electrocardiograms. The findings were interpreted as a pattern of autosomal recessive inheritance. Subsequent reports identified LQTS families with normal hearing (Romano-Ward Syndrome) having a pattern of occurrence suggesting autosomal dominant inheritance.

DESIGN NARRATIVE:

Beginning in 1985, patients and their unaffected relatives were longitudinally followed in this multicenter study to develop and validate widely applicable clinical criteria for stratifying the risk of life-threatening arrhythmias. A population of genetically deaf students was surveyed to identify additional families with the unique association of Long QT Syndrome and congenital deafness in order to expand the data base for genetic studies in the recessive form of the disorder, the Jervell and Lange-Nielsen Syndrome. Pedigrees of selected Long QT Syndrome families were recorded to better understand the inheritance of the dominant form of the disorder, the Romano-Ward Syndrome. Genetic studies were conducted using human leukocyte antigen and other protein markers in order to investigate the gene locus for the autosomal dominant form of the syndrome. A select group of 30 patients and 30 unaffected relatives had 24-hour Holter monitoring, treadmill exercise, Valsalva maneuver and handgrip stress tests to determine if the patients had a unique cardiovascular response to autonomic dysfunction.

The study was renewed in 1993. The renewal had six aims. The first examined genetic heterogeneity in LQTS by testing for Harvey-ras-1 gene linkage in the existing well-characterized LQTS families with evidence of a major gene by segregation analysis; in LQTS families that did not show Harvey-ras- 1 linkage, a search for other closely linked genetic markers was initiated. The second aim explored by segregation analysis the likelihood that a second gene coexisted with the Harvey-ras-1 gene to explain a more malignant disease process in some LQTS families than in others. The third established normal standards for six quantitative repolarization parameters on a healthy population (n=4,000) using digitized ECG recordings, and biomedical and statistical techniques with adjustment for age, gender, race, and heart rate. The fourth aim continued the existing LQTS registry with ongoing enrollment of new families and follow-up of new and existing LQTS pedigrees (n=370 families) in order to provide a central repository for this disorder, especially as it related to the natural history of this disorder and ongoing genetic analyses. The fifth aim investigated the static (12-lead ECG) and dynamic (24-hour Holter ECG) aspects of ventricular repolarization in LQTS families showing Harvey-ras gene linkage to upgrade the ECG categorization of delayed repolarization using the Harvey-ras- 1 marker as the gold standard to identify affected and unaffected individuals. The sixth aim continued the prospective longitudinal follow-up study of LQTS families to better understand the long-term clinical course of this disorder; time-dependent survivorship analyses were performed to evaluate the effects of various clinical features, repolarization severity (QTc length), Harvey-ras-I gene linkage, and therapeutic efficacy with antiadrenergic therapy (if data permits) on outcome event rates (syncope and sudden death) in the LQTS probands.

The study has been renewed several times to: expand the pedigrees of LQTS families and family members enrolled in the registry; identify new LQTS gene mutations and expand the number of gene-identified affected and unaffected members in LQTS families with known gene mutations; investigate phenotype-genotype relationships in 200 genotyped families involving 1,200 affected and unaffected family members regarding the clinical course of LQTS, T-wave repolarization, triggering factors for cardiac events, and co-morbidity associations, all by genotype. The study remains a multicenter project with six clinical centers, a genetic component involving four molecular genetic labs, a statistical genetic component, a biostatistical component, and a coordinating center.

Study Type

Observational

Enrollment (Actual)

2125

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • New York
      • Rochester, New York, United States, 14642
        • University of Rochester

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

No older than 100 years (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

As of the 2013 closeout report, 1329 probands with clinical dx of LQTS and members of their extended families have been enrolled in the LQTS Registry. By ECG classification, this includes 3420 probands and affected family members, 3533 unaffected family members, and 2105 family members with borderline QTc. Of those, 2125 have had mutations identified.

Description

Probands are required to have clinical dx of LQTS. Family members are also invited to participate regardless of their dx.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
None. This is an observational study.
Time Frame: By study end
By study end

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • Principal Investigator: Arthur Moss, University of Rochester

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

August 1, 1985

Primary Completion (Actual)

April 1, 2013

Study Completion (Actual)

April 1, 2013

Study Registration Dates

First Submitted

May 25, 2000

First Submitted That Met QC Criteria

May 25, 2000

First Posted (Estimate)

May 26, 2000

Study Record Updates

Last Update Posted (Estimate)

October 22, 2015

Last Update Submitted That Met QC Criteria

October 20, 2015

Last Verified

October 1, 2015

More Information

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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