Hereditary Hyperekplexia—Autoimmune Diseases

Your body’s immune system protects you from disease and infection. But if you have an autoimmune disease, your immune system attacks healthy cells in your body by mistake. Autoimmune diseases can affect many parts of the body.

No one is sure what causes autoimmune diseases. They do tend to run in families. Women – particularly African-American, Hispanic-American, and Native-American women – have a higher risk for some autoimmune diseases.

There are more than 80 types of autoimmune diseases, and some have similar symptoms. This makes it hard for your health care provider to know if you really have one of these diseases, and if so, which one. Getting a diagnosis can be frustrating and stressful. Often, the first symptoms are fatigue, muscle aches and a low fever. The classic sign of an autoimmune disease is inflammation, which can cause redness, heat, pain and swelling.

The diseases may also have flare-ups, when they get worse, and remissions, when symptoms get better or disappear. Treatment depends on the disease, but in most cases one important goal is to reduce inflammation. Sometimes doctors prescribe corticosteroids or other drugs that reduce your immune response.

• Autoimmune disorders (Medical Encyclopedia)
• Complement (Medical Encyclopedia)

Hereditary hyperekplexia is a condition in which affected infants have increased muscle tone (hypertonia) and an exaggerated startle reaction to unexpected stimuli, especially loud noises. Following the startle reaction, infants experience a brief period in which they are very rigid and unable to move. During these rigid periods, some infants stop breathing, which, if prolonged, can be fatal. This condition may explain some cases of sudden infant death syndrome (SIDS), which is a major cause of unexplained death in babies younger than 1 year. Infants with hereditary hyperekplexia have hypertonia at all times, except when they are sleeping.Other signs and symptoms of hereditary hyperekplexia can include muscle twitches when falling asleep (hypnagogic myoclonus) and movements of the arms or legs while asleep. Some infants, when tapped on the nose, extend their head forward and have spasms of the limb and neck muscles. Rarely, infants with hereditary hyperekplexia experience recurrent seizures (epilepsy).The signs and symptoms of hereditary hyperekplexia typically fade by age 1. However, older individuals with hereditary hyperekplexia may still startle easily and have periods of rigidity, which can cause them to fall down. Some individuals with this condition have a low tolerance for crowded places and loud noises. Some affected people have persistent limb movements during sleep. Affected individuals who have epilepsy have the disorder throughout their lives.