About familial dysautonomia, type ii

What is familial dysautonomia, type ii?

The hereditary sensory neuropathies (HSN) include 4-6 similar but distinct inherited degenerative disorders of the nervous system (neurodegenerative) that frequently progress to loss of feeling, especially in the hands and feet. The classification of these diseases is complicated, and sometimes a source of disagreement among the experts.

Hereditary sensory neuropathy type IV (HSN4) is a rare genetic disorder characterized by the loss of sensation (sensory loss), especially in the feet and legs and, less severely, in the hands and forearms. The sensory loss is due to abnormal functioning of small, unmyelinated nerve fibers and portions of the spinal cord that control responses to pain and temperature as well as other involuntary or automatic body processes. Sweating is almost completely absent with this disorder. Mental retardation is usually present.

The disorder is inherited as an autosomal recessive trait. The gene involved is located on chromosome 1.

HSNs of various types may attack a single nerve (mononeuropathy) or many nerves simultaneously (polyneuropathy). The resulting symptoms may involve sensory, motor, reflex, or blood vessel (vasomotor) functions.

What are the symptoms for familial dysautonomia, type ii?

An infant born with familial dysautonomia typically has poor sucking ability, impaired swallowing reflexes, Poor muscle tone (hypotonia), and/or abnormally low body temperature (hypothermia). Infants with this disorder may have cold hands and feet and experience unstable body temperature (from 94 to 108 degrees) during the course of infectious diseases. Profuse sweating and drooling may also occur. Crying without tears is one of the most striking symptoms of familial dysautonomia. Sometimes a Lack of tears and insensitivity of the eyes to Pain from foreign objects (corneal anesthesia) can lead to Inflammation of the corneas and ulcerations in the eyes.

Children with familial dysautonomia have a decreased perception of Pain and lack of sensitivity to hot and/or cold temperatures; this can result in unnoticed injuries to the skin. Unstable blood pressure is usually present in infants with familial dysautonomia. Blood pressure readings may vary greatly and may be abnormally high or low.

Other symptoms of familial dysautonomia may include the absence of the sense of taste, impaired speech, and/or red blotches on the skin that appear with emotional excitement. Approximately 40 percent of children with this disorder experience episodes of vomiting. Occasionally there may be skeletal defects, absence of tendon reflexes, stunted height, and/or repeated episodes of pneumonia due to the inhalation of food (aspiration).

By adolescence, 95 percent of individuals with familial dysautonomia have evidence of side-to side spinal curvature (scoliosis). In addition, they may experience increased sweating and an accelerated heart rate. A decreased awareness of Pain makes it difficult for children with this disorder to be aware of injuries; bone fractures may go unrecognized. Other symptoms that may appear during adolescence include weakness, leg cramps, and/or difficulty concentrating. Personality changes may also occur including depression, irritability, inability to sleep (insomnia), and/or negativism.

Approximately 20 percent of adults with familial dysautonomia over 20 years of age develop kidney insufficiency. Neurological deterioration also appears and unsteadiness in walking may become more apparent at this age.

A medical test is available that can determine if an infant has familial dysautonomia. Histamine is injected under the skin and response is measured along nerve cell fibers (axon flare). A lack of response confirms the diagnosis of familial dysautonomia.

What are the causes for familial dysautonomia, type ii?

Familial dysautonomia is inherited as a recessive genetic trait. Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother. In recessive disorders, the condition does not appear unless a person inherits the same defective gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is 25 percent. Fifty percent of their children risk being carriers of the disease, but generally will not show symptoms of the disorder. Twenty-five percent of their children may receive both normal genes, one from each parent, and will be genetically normal (for that particular trait). The risk is the same for each pregnancy.

Researchers have identified the gene that causes familial dysautonomia. Two mutations of the gene known as IKBKAP can cause FD. A carrier test is now available for all Ashkenazi Jews. Consult your local physician for details.

What are the treatments for familial dysautonomia, type ii?

Physical therapy, chest physiotherapy, occupational therapy, feeding facilitation, and/or speech therapy may also be useful to alleviate the symptoms of familial dysautonomia.

People with familial dysautonomia may also benefit from a variety of other orthopedic and ocular (vision) aids.

Genetic counseling will be of benefit for patients with familial dysautonomia and their families.

What are the risk factors for familial dysautonomia, type ii?

Familial dysautonomia is a rare genetic disorder that affects males and females in equal numbers. This disorder primarily affects infants of Ashkenazi Jewish or Eastern European ancestry; approximately 1 in 30 people of East European Jewish ancestry are thought to be carriers of the defective gene that causes this disorder.

Is there a cure/medications for familial dysautonomia, type ii?

Drugs used to relieve the symptoms of familial dysautonomia include diazepam, metoclopramide, and chloral hydrate. Artificial tears may be needed to lubricate the eyes.

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