Common Rare Disease FAQs
Learn more about this rare disease by viewing some common rare disease FAQs below.
General Disease Information
An infantile spasm (IS) is a specific type of seizure seen in an epilepsy syndrome of infancy and childhood known as West Syndrome. West Syndrome is characterized by infantile spasms, developmental regression, and a specific pattern on electroencephalography (EEG) testing called hypsarrhythmia (chaotic brain waves). The onset of infantile spasms is usually in the first year of life, typically between 4-8 months. The seizures primarily consist of a sudden bending forward of the body with stiffening of the arms and legs; some children arch their backs as they extend their arms and legs. Spasms tend to occur upon awakening or after feeding, and often occur in clusters of up to 100 spasms at a time. Infants may have dozens of clusters and several hundred spasms per day. Infantile spasms usually stop by age five, but may be replaced by other seizure types. Many underlying disorders, such as birth injury, metabolic disorders, and genetic disorders can give rise to spasms, making it important to identify the underlying cause. In some children, no cause can be found.
During an MS attack, inflammation occurs in areas of the white matter* of the central nervous system in random patches called plaques. This process is followed by destruction of myelin, the fatty covering that insulates nerve cell fibers in the brain and spinal cord. Myelin facilitates the smooth, high-speed transmission of electrochemical messages between the brain, the spinal cord, and the rest of the body; when it is damaged, neurological transmission of messages may be slowed or blocked completely, leading to diminished or lost function. The name "multiple sclerosis" signifies both the number (multiple) and condition (sclerosis, from the Greek term for scarring or hardening) of the demyelinated areas in the central nervous system.
Hypophosphatasia is an inherited disorder that affects the development of bones and teeth. This condition disrupts a process called mineralization, in which minerals such as calcium and phosphorus are deposited in developing bones and teeth. Mineralization is critical for the formation of bones that are strong and rigid and teeth that can withstand chewing and grinding.
The signs and symptoms of hypophosphatasia vary widely and can appear anywhere from before birth to adulthood. The most severe forms of the disorder tend to occur before birth and in early infancy. Hypophosphatasia weakens and softens the bones, causing skeletal abnormalities similar to another childhood bone disorder called rickets. Affected infants are born with short limbs, an abnormally shaped chest, and soft skull bones. Additional complications in infancy include poor feeding and a failure to gain weight, respiratory problems, and high levels of calcium in the blood (hypercalcemia), which can lead to recurrent vomiting and kidney problems. These complications are life-threatening in some cases.
The forms of hypophosphatasia that appear in childhood or adulthood are typically less severe than those that appear in infancy. Early loss of primary (baby) teeth is one of the first signs of the condition in children. Affected children may have short stature with bowed legs or knock knees, enlarged wrist and ankle joints, and an abnormal skull shape. Adult forms of hypophosphatasia are characterized by a softening of the bones known as osteomalacia. In adults, recurrent fractures in the foot and thigh bones can lead to chronic pain. Affected adults may lose their secondary (adult) teeth prematurely and are at increased risk for joint pain and inflammation.
The mildest form of this condition, called odontohypophosphatasia, only affects the teeth. People with this disorder typically experience abnormal tooth development and premature tooth loss, but do not have the skeletal abnormalities seen in other forms of hypophosphatasia.
The National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health), supports research to find ways to treat and prevent lipid storage disorders. This research includes clinical studies by the NINDS Developmental and Metabolic Neurology Branch.
Gaucher disease is an inherited metabolic disorder in which harmful quantities of a fatty substance called glucocerebroside accumulate in the spleen, liver, lungs, bone marrow, and sometimes in the brain. There are three types of Gaucher disease. The first category, called type 1, is by far the most common. Patients in this group usually bruise easily and experience fatigue due to anemia and low blood platelets. They also have an enlarged liver and spleen, skeletal disorders, and, in some instances, lung and kidney impairment. There are no signs of brain involvement. Symptoms can appear at any age. In type 2 Gaucher disease, liver and spleen enlargement are apparent by 3 months of age. Patients have extensive and progressive brain damage and usually die by 2 years of age. In the third category, called type 3, liver and spleen enlargement is variable, and signs of brain involvement such as seizures gradually become apparent. All Gaucher patients exhibit a deficiency of an enzyme called glucocerebrosidase that is involved in the breakdown and recycling of glucocerebroside. The buildup of this fatty material within cells prevents the cells and organs from functioning properly. Gaucher disease is one of several lipid storage diseases.
The National Institute of Neurological Disorders and Stroke (NINDS), and other Institutes of the National Institutes of Health (NIH), conduct research related to Pompe disease in laboratories at the NIH, and also support additional research through grants to major medical institutions across the country. Much of this research focuses on finding better ways to prevent, treat, and ultimately cure disorders such as Pompe disease.
Pompe disease is a rare (estimated at 1 in every 40,000 births), inherited and often fatal disorder that disables the heart and muscles. It is caused by mutations in a gene that makes an enzyme called alpha-glucosidase (GAA). Normally, the body uses GAA to break down glycogen, a stored form of sugar used for energy. But in Pompe disease, mutations in the GAA gene reduce or completely eliminate this essential enzyme. Excessive amounts of glycogen accumulate everywhere in the body, but the cells of the heart and skeletal muscles are the most seriously affected. Researchers have identified up to 70 different mutations in the GAA gene that cause the symptoms of Pompe disease, which can vary widely in terms of age of onset and severity. The severity of the disease and the age of onset are related to the degree of enzyme deficiency.
Early onset (or infantile Pompe disease is the result of complete or near complete deficiency of GAA. Symptoms begin in the first months of life, with feeding problems, poor weight gain, muscle weakness, floppiness, and head lag. Respiratory difficulties are often complicated by lung infections. The heart is grossly enlarged. More than half of all infants with Pompe disease also have enlarged tongues. Most babies with Pompe disease die from cardiac or respiratory complications before their first birthday.
Late onset (or juvenile/adult) Pompe disease is the result of a partial deficiency of GAA. The onset can be as early as the first decade of childhood or as late as the sixth decade of adulthood. The primary symptom is muscle weakness progressing to respiratory weakness and death from respiratory failure after a course lasting several years. The heart may be involved but it will not be grossly enlarged. A diagnosis of Pompe disease can be confirmed by screening for the common genetic mutations or measuring the level of GAA enzyme activity in a blood sample -- a test that has 100 percent accuracy. Once Pompe disease is diagnosed, testing of all family members and consultation with a professional geneticist is recommended. Carriers are most reliably identified via genetic mutation analysis.
Most people experience their first symptoms of MS between the ages of 20 and 40, but a diagnosis is often delayed. This is due to both the transitory nature of the disease and the lack of a specific diagnostic test-specific symptoms and changes in the brain must develop before the diagnosis is confirmed.
Although scientists have documented cases of MS in young children and elderly adults, symptoms rarely begin before age 15 or after age 60. Whites are more than twice as likely as other races to develop MS. In general, women are affected at almost twice the rate of men; however, among patients who develop the symptoms of MS at a later age, the gender ratio is more balanced.
MS is five times more prevalent in temperate climates-such as those found in the northern United States, Canada, and Europe-than in tropical regions. Furthermore, the age of 15 seems to be significant in terms of risk for developing the disease: some studies indicate that a person moving from a high-risk (temperate) to a low-risk (tropical) area before the age of 15 tends to adopt the risk (in this case, low) of the new area and vice versa. Other studies suggest that people moving after age 15 maintain the risk of the area where they grew up.
These findings indicate a strong role for an environmental factor in the cause of MS. It is possible that, at the time of or immediately following puberty, patients acquire an infection with a long latency period. Or, conversely, people in some areas may come in contact with an unknown protective agent during the time before puberty. Other studies suggest that the unknown geographic or climatic element may actually be simply a matter of genetic predilection and reflect racial and ethnic susceptibility factors.
Periodically, scientists receive reports of MS "clusters." The most famous of these MS "epidemics" took place in the Faeroe Islands north of Scotland in the years following the arrival of British troops during World War II. Despite intense study of this and other clusters, no direct environmental factor has been identified. Nor has any definitive evidence been found to link daily stress to MS attacks, although there is evidence that the risk of worsening is greater after acute viral illnesses.
Enzyme replacement therapy is very beneficial for type 1 patients and most type 3 patients with this condition.
Without enzyme replacement therapy, the hearts of babies with infantile onset Pompe disease progressively thicken and enlarge. These babies die before the age of one year from either cardiorespiratory failure or respiratory infection. For individuals with late onset Pompe disease, the prognosis is dependent upon the age of onset. In general, the later the age of onset, the slower the progression of the disease. Ultimately, the prognosis is dependent upon the extent of respiratory muscle involvement.
The prognosis for children with IS is dependent on the underlying causes of the seizures. The intellectual prognosis for children with IS is generally poor because many babies with IS have neurological impairment prior to the onset of spasms. Spasms usually resolve by mid-childhood, but more than half of the children with IS will develop other types of seizures. There appears to be a close relationship between IS and Lennox-Gastaut Syndrome, an epileptic disorder of later childhood.
No one knows exactly how many people have MS. It is believed that, currently, there are approximately 250,000 to 350,000 people in the United States with MS diagnosed by a physician. This estimate suggests that approximately 200 new cases are diagnosed each week.
Highly effective enzyme replacement therapy is available for most patients with types 1 and 3 Gaucher disease. This therapy decreases liver and spleen size, reduces skeletal anomalies, and successfully reverses other symptoms of the disorder, including abnormal blood counts. Bone marrow transplantation (a procedure to replace damaged or destroyed blood-forming cells) can reverse the non-neurological effects of type 1 Gaucher disease, but it carries a high mortality rate due to imperfect donor matches. This procedure has been replaced by enzyme replacement therapy. There is no effective treatment for severe brain damage that may occur in patients with types 2 and 3 Gaucher disease.
Individuals with Pompe disease are best treated by a team of specialists (such as cardiologist, neurologist, and respiratory therapist) knowledgeable about the disease, who can offer supportive and symptomatic care. The discovery of the GAA gene has led to rapid progress in understanding the biological mechanisms and properties of the GAA enzyme. As a result, an enzyme replacement therapy has been developed that has shown, in clinical trials with infantile-onset patients, to decrease heart size, maintain normal heart function, improve muscle function, tone, and strength, and reduce glycogen accumulation. A drug called alglucosidase alfa (Myozyme©), has received FDA approval for the treatment of Pompe disease.
Treatment with corticosteroids such as prednisone is standard, although serious side effects can occur. Several newer antiepileptic medications, such as topiramate may ease some symptoms. Some children have spasms as the result of brain lesions, and surgical removal of these lesions may result in improvement.
The NINDS supports broad and varied programs of research on epilepsy and other seizure disorders. This research is aimed at discovering new ways to prevent, diagnose, and treat these disorders and, ultimately, to find cures for them. Hopefully, more effective and safer treatments, such as neuroprotective agents, will be developed to treat IS and West Syndrome.