Jarvell-Lange Nielsen Syndrome is rare disorder characterized by the hearing loss from the birth of the infant and problem with the normal heart rhythm. The severity of this condition varies from the different cases with some not presenting any apparent symptoms to others developing abnormal heart beats that can result in cardiac arrest and death. More than half of the cases left untreated results in the death of the affected individual before the age of 15. This syndrome is estimated to affect around 1 to 6 per 1,000,000 live births, although the prevalence appears to be higher in Norway and Sweden.
Causes
This develops as the result of the mutation in the genes KCNE1 and KCNQ1 which are responsible for the production of proteins that are essential for the formation of a channel across cell membranes. The transportation of the potassium ions through these channels is important for the normal function of the ear and the cardiac muscle. In most of the cases, the genetic mutation in the gene KCNQ1 is responsible for the cause of this condition which affects the normal movement of the potassium channels thus resulting in the features characteristic of this condition. This is inherited in an autosomal recessive pattern meaning both the copies of the genes from the parents are defective. In most of the cases, the parents of the affected individual are normal and are the carriers of the defective gene.
Symptoms
The symptoms are usually evident at the birth or during the early childhood that includes hearing loss affecting both the ears and low levels of iron that can cause iron deficiency anemia. The most common cardiac problem is the loss of consciousness accompanied by the abnormally rapid heart rhythm (torsade de pointes). This can continue to cause a serious condition known as ventricular fibrillation that affects the electrical activity of the heart that can result in a cardiac arrest or even sudden death.
Diagnosis
The diagnosis is based on the evaluation of the patient’s history and the specialized test known as an electrocardiogram (ECG or EKG). Children with the congenital sensorineural hearing loss, history of fainting or sudden cardiac arrest should be evaluated for this syndrome. The ECG will record abnormal electrical patterns of the heart which are also characteristic of this condition. The molecular genetic testing can confirm the condition with the identification of the genetic mutation that is responsible for this syndrome. It is also important to diagnose these individuals before a surgery to prevent the severe cardiac complications that can develop.
Treatment
The treatment is based on treating the hearing loss and to prevent the cardiac arrest or complications. The hearing loss can be treated with the cochlear implant that improves the hearing by stimulating the nerve fibers of the inner ear. Medications for the cardiac abnormalities can lower the workload of the heart or in some cases, a surgical procedure may be required to remove certain nerves going to the heart. The automatic cardioverter-defibrillator may also be implanted that identifies the abnormal heartbeat and delivers the electrical impulse. In some of the cases, genetic counseling may be beneficial for the affected individuals and their families.
References
https://rarediseases.org/rare-diseases/jervell-and-lange-nielsen-syndrome/
https://ghr.nlm.nih.gov/condition/jervell-and-lange-nielsen-syndrome#inheritance
