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Jervell and Lange-Nielsen Syndrome
Wednesday, 17 November 2004
Thursday, 09 December 2004

What

Jervell and Lange-Nielsen syndrome (JLNS) is a rare, inherited, genetic disorder characterized by profound deafness and disturbances of heart rhythm (arrhythmias) that may lead to the loss of consciousness and even sudden death. The risk of sudden death is due to the prolongation of the electrical impulse that leads to contraction and relaxation of the heart (QT interval). A prolonged QT interval does predispose an individual to developing rapid arrhythmias.

Who

JLNS is estimated to occur in 1.6 to 6 persons per million, reflecting the fact that is a relatively rare disorder. There is a high concentration of JLNS patients in Norway, where the occurrence is 1 in 200,000 persons. JLNS is also more common in communities where marriage between blood relatives occurs.

Signs and Symptoms

Individuals diagnosed with JLNS will have some or all of the following signs and symptoms: 1. Sensorineural deafness: a profound form of hearing loss that occurs from birth due to problems with relay of sound messages from the middle or inner ear to the brain 2. Episodes of loss of consciousness (syncope), especially with stress, exercise or fear. 3. Intermittent episodes of abnormal heart rhythms (arrhythmia) episodes that result in irregular, rapid, heartbeats. 4. Seizures may occur during episodes of arrhythmia due to the lack of oxygen to the brain. 5. The remainder of the physical examination is usually normal.

Possible Causes

This rare genetic condition is inherited in an autosomal recessive manner and may be caused by a defect in the KCNQ1 gene on chromosome 11. This gene codes for a protein that forms a potassium channel in the heart muscle. A DNA mutation in this gene leads to abnormal formation of this channel, thus causing abnormal electrical conduction in the heart. Mutations in this gene are found in over 90% of people with JLNS. People with JLNS can have one defective copy of the gene (called “carriers” or “heterozygotes”) or two copies (“homozygotes”). Carriers of JLNS mutations usually have normal hearing, but may exhibit symptoms associated with a prolonged QT interval.

Diagnosis

Children with congenital hearing loss and episodes of fainting should be thoroughly evaluated, since either or both symptoms can be acquired and not genetic. Diagnosis of JLNS can be made based on detailed family history, past medical history, physical exams and specialized tests. The physical examination is usually normal. An electrocardiogram (EKG) is usually obtained and may reveal a prolonged QT interval. Deaf children who are not diagnosed with JLNS in the neonatal period (right after birth) should have an EKG if they have seizures or syncope (fainting). Prenatal diagnosis is generally not available. However, families with a known JLNS mutation may find a doctor who can contact a specialized laboratory that offers custom testing for genetic counseling purposes.

Treatment

Cochlear implants can treat the hearing impairment of children with JLNS, and recent evidence suggests better outcomes if the surgery is performed before 2 years of age. Medications may be indicated for preventing episodes of cardiac arrhythmia. Also, an implanted pacemaker could be helpful as well. In patients who experience numerous episodes of syncope, a surgery implanting a defibrillator (ICD, implantable cardiac defibrillator) may be necessary to lower the risk of sudden death. Left stellate ganglion block (procedure that affects fibers within a bundle of nerves in the chest that influences ventricular function) has been done to treat patients with a persistently prolonged QT interval. It is also important to avoid drugs that can increase the length of QT interval and events or activities that can trigger an arrhythmia (including competitive sports, scary movies, amusement park rides and jumping into cold water, to name a few).

Prognosis

Very little information is available about life expectancy of people diagnosed with JLNS. It is known that severe prolonged QT intervals are associated with increased risk of sudden infant death syndrome (SIDS). More than 50% of children with untreated JLNS die before age 15, although there are some case accounts of people who have survived several syncopal episodes in adulthood. However, with treatment and prevention of syncopal episodes and cardiac arrhythmias, children with JLNS can potentially live well into adulthood.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

Cardiac Arrhythmias Research and Education Foundation (CARE)
Education regarding this potentially fatal arrhythmia.

European Long QT Syndrome Information Center
Comprehensive information about this syndrome, as well as a message board.

Earaces.com
Information about sensorineural hearing loss.

Cardio-Auditory Syndrome of Jervell and Lange-Nielsen
Compilation of definitions of JLNS from numerous sources.

Sudden arrhythmia death syndrome foundation (SADS)
Great link for parents and children to read about others affected, ongoing research, international symposiums and support groups.

Google Search for Jervell and Lange-Nielsen Syndrome

References and Sources

OMIM: Jervell and Lange-Nielsen Syndrome www3.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=220400 Jervell and Lange-Nielsen Syndrome www.genetests.org/servlet/access?id=8888890&db=genetests&fcn=y&dontshowglossarylinks=yes&key=hihDVQxjwZCSA&filename=/profiles/jln/index.html Jervell and Lange-Nielsen Syndrome www.gasnet.org/pediatric-syndromes/jervell.php