Article: Jervell and Lange-Nielsen syndrome

What is Jervell and Lange-Nielsen syndrome?

Jervell and Lange-Nielsen syndrome is a condition that causes profound hearing loss and a disruption of the heart's normal rhythm (arrhythmia). This disorder is a form of long QT syndrome, which is a heart condition that causes the cardiac muscle to take longer than usual to recharge between beats. If untreated, the irregular heartbeats can lead to fainting (syncope), seizures, or sudden death.

How common is Jervell and Lange-Nielsen syndrome?

Jervell and Lange-Nielsen syndrome is uncommon; it affects an estimated 1.6-6 in 1 million children. This disorder is responsible for less than 10 percent of all cases of long QT syndrome.

What genes are related to Jervell and Lange-Nielsen syndrome?

Mutations in the KCNE1 and KCNQ1 genes cause Jervell and Lange-Nielsen syndrome.

The proteins produced by these two genes work together to form a channel that transports positively charged potassium atoms (ions) out of cells. The movement of potassium ions through these channels is critical for maintaining the normal functions of the inner ear and cardiac muscle.

About 90 percent of cases of Jervell and Lange-Nielsen syndrome are caused by mutations in the KCNQ1 gene; KCNE1 mutations are responsible for the remaining 10 percent of cases. Mutations in these genes alter the usual structure and function of potassium channels or prevent the assembly of normal channels. These changes disrupt the flow of potassium ions in the inner ear and in cardiac muscle, leading to the hearing loss and irregular heart rhythm characteristic of Jervell and Lange-Nielsen syndrome.

How do people inherit Jervell and Lange-Nielsen syndrome?

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene must be altered in each cell for a person to be affected by the disorder. Most often, the parents of a child with an autosomal recessive disorder are not affected but are carriers of one copy of the altered gene. Carriers of a KCNQ1 or KCNE1 mutation may have some signs and symptoms related to Jervell and Lange-Nielsen syndrome.