Gaucher disease

Gaucher Disease is an autosomal recessive disease and the most prevalent Lysosomal Storage Disorder (LSD), with an incidence of about 1 in 20,000 live births. Despite the fact that Gaucher Disease consists of a phenotype, with varying degrees of severity, it has been sub-divided in three subtypes according to the presence or absence of neurological involvement. It is also the most common genetic disease affecting Ashkenazi Jewish people (Eastern, Central and Northern European ancestry), with a carrier frequency of 1 in 10 (Dr. John Barranger and Dr. Ed Ginns 1989). This panethnic disease involves many organ systems, such as liver, spleen, lungs, brain, metabolism and bone marrow.

Gaucher Disease results from a specific enzyme deficiency in the body, caused by a genetic mutation received from both parents. The disease course is quite variable, ranging from no outward symptoms to severe disability and death. Carrier status can be detected through blood or saliva to identify potential carriers of the Gaucher gene. Gaucher disease can be diagnosed early through a blood test. Fortunately, effective treatments are available for some variants of the disease.

Symptoms
Gaucher disease can cause:
• Anemia
• Fatigue
• Easy Bruising and Bleeding
• Nosebleeds
• Osteoporosis
• Bone pain and easily broken bones
• Swollen stomach due to enlarged liver and/or spleen

In 1882, a French physician named Philippe Charles Ernest Gaucher (pronounced: go-SHAY) first described a clinical syndrome in a 32-year-old woman whose liver and spleen were enlarged. The most common symptoms of Gaucher Disease are enlargement of the liver and spleen, anemia, reduced platelets (resulting in easy bruising and long clotting times), bone pain ("bone crises"), bone infarctions often leading to damage to the shoulder or hip joints, and a generalized demineralization of the bones (osteoporosis). The weakening of the bones can then lead to spontaneous fractures. The course of the disease is quite variable, ranging from no overt symptoms to skeletal problems, liver or spleen damage, bleeding, or other problems. There are indications of an increased risk of multiple myeloma, a type of slow growing cancer in the bones, in older individuals with Gaucher disease. Because enzyme therapy has only been available since 1991, there are no data regarding this finding in individuals who are receiving the enzyme replacement therapy.

The characteristics just listed refer primarily to the Type 1 form of the disease. This is often called the adult form, although the cause is present from the time of conception. Type 1 Gaucher disease occurs worldwide in all populations, but is most prevalent in the Ashkenazi Jewish population (the Jews of Eastern European ancestry). Within this population, Type 1 Gaucher disease occurs at a rate of 1 in 450 live births, and is the most common genetically-based disease affecting Jewish people.

There are other forms of Gaucher Disease which, in addition to the liver, spleen, and bone complications characteristic of Type 1 Gaucher Disease, also result in acute neurological symptoms. Type 2 Gaucher Disease, called the acute neuropathic form, is characterized by brainstem abnormalities and is usually fatal during the first three years of life. Type 2 Gaucher Disease shows no ethnic predilection, and occurs rarely, with an incidence of 1 in 100,000 live births. Type 3 Gaucher Disease, the chronic neuropathic form, also shows no ethnic predilection, and is estimated to occur in 1 in 50,000 live births. The neurologic symptoms of Type 3 Gaucher Disease are slowly progressive and appear later in childhood than the symptoms of Type 2 Gaucher Disease. Neurologic symptoms of Type 3 Gaucher Disease include incoordination, mental deterioration, and myoclonic seizures. There is a subclassification of Type 3, called Norbottnian Gaucher Disease, named for the region in Sweden where it has been identified. The slowly progressive neurologic symptoms of Norbottnian Gaucher Disease may not occur until early adulthood.

Prevalence and transmission
Gaucher Disease can affect anyone - regardless of ethnicity, age or gender. Gaucher disease an inborn error of metabolism. Inborn metabolic disorders are those conditions resulting from a specific malfunction in one or more of the body's many individual chemical processes. Although there are at least 34 mutations known to cause Gaucher Disease, there are 4 genetic mutations which account for 95% of the Gaucher Disease in the Ashkenazi Jewish population, and 50% of the Gaucher Disease in the general population. These can be identified through a blood test.

The carrier rate for the mutations which cause Gaucher Disease may be as high as 1 in 10 Jewish people of Eastern European ancestry, and 1 in 200 of the general population. Gaucher Disease is transmitted as an autosomal recessive; that is, it occurs equally among males and females, and both parents must carry the mutation for the child to have the disease. If both parents are carriers, then there is a 1 in 4 chance that the child will have Gaucher Disease, a 1 in 2 chance that the child will not have the disease but will be a carrier, and a 1 in 4 chance that the child will neither have the disease nor be a carrier.

Clinical course
The symptoms associated with Gaucher Disease result from the accumulation of a fatty substance, a lipid called glucocerebroside. This lipid is a byproduct of the normal recycling of red blood cells. When the gene with the instructions for producing an enzyme to break down this byproduct is defective, the lipid accumulates. Gaucher Disease is, therefore, a lipid storage disease, and is the most common disease of this type. The lipid is found in many places in the body, but most commonly in the macrophages ("big-eater" cells) in the bone marrow. There it interferes with normal bone marrow functions, such as production of platelets (leading to bleeding and bruising) and red blood cells (leading to anemia).

The presence of glucocerebroside seems to also trigger the loss of minerals in the bones, causing the bones to weaken, and can interfere with the bone's blood supply, causing areas of bone-death, or "infarctions." The most immediate human cost of Type I Gaucher Disease is related to the loss of function when a hip or shoulder becomes infarcted or a long bone fractures, the great pain experienced during reduced blood flow to the bones ("bone crises"), abdominal problems related to massive enlargement of the liver and spleen, poor blood clotting, and anemia. Type 2 and Type 3 Gaucher Disease result in severe neurological impairment or early demise.

Testing for Gaucher disease
Gaucher Disease can be diagnosed early through a blood test. Carrier status can be detected through blood or saliva. There are Gaucher specialists throughout the country who can diagnose, evaluate and recommend proper treatment. The testing process can be done at a hospital, Gaucher specialist's office, or through your family physician. Your physician can draw blood that would then be sent to a specific laboratory for testing.

The NGF is committed to keeping the public informed about all aspects of Gaucher Disease including treatment options, testing and services available for Gaucher patients, physicians and treatment providers. For your convenience, the NGF has provided a diagnostic lab list and other testing websites to assist you and your physician find Diagnostic and Gaucher testing labs throughout the country.

(1) Genetic Testing Website: www.genetests.org
(2) Lab Corp: www.labcorp.com

Gaucher disease testing. An enzyme assay test measures glucocerebrosidase (GC) activity in leukocytes, fibroblasts, or urine. Individuals who are affected with Gaucher Disease will have very low levels of enzyme activity. There are four common mutations of the GC gene: N370S, L444P, 84gg and IVS2[+1]. DNA analysis for these four mutations detects 90% to 95% of the mutations associated with Gaucher Disease in the Ashkenazi Jewish population, and 50% to 75% of the associated mutations in the general population. Neither disease type nor severity of disease is defined by enzyme assay. DNA analysis is used in combination with the enzyme assay test to diagnose Gaucher Disease and is helpful in defining the subtype.

Gaucher carrier testing. Approximately 1 in 60,000 people have Gaucher Disease. However, among Jews of Eastern European (Ashkenazi) descent, one in 450 people will have the disorder, and the carrier rate is approximately 1 in 15. Carrier status can be detected through a blood or saliva test. The testing process can be done at a hospital, Gaucher specialist's office, or through your family physician. Laboratory assay tests use chromosomes, DNA, RNA, and genes to determine the genetic status of a person who is at high risk for a particular condition. For detailed information on genetic testing, you or your physician can visit any of the links listed above.

Gaucher treatments and drugs
Treatments and drugs for Gaucher disease type 1, the most common form of the disease, may vary depending on the severity of each patient's disease and the course of treatment your physician determines. Enzyme replacement therapy (ERT) is administered intravenously for the non-neurological manifestations of types 1 and 3. There are no treatments available for type 2, the most fatal form of the disease, which presents in infancy and causes demise within the first two to three years.

There are three enzyme replacement therapies (ERT) available for treatment of Gaucher and one oral medication which may be taken by those over 18-years-old and/or have a mild case of Gaucher. The course of treatment is a decision that you and your doctor must decide based on prognosis and other extenuating factors.

Research and clinical trials are ongoing for additional treatments and/or a cure for Gaucher disease, including cell and gene therapy.

Information on drugs used to treat Gaucher disease can be accessed on the National Gaucher Foundation website: https://www.gaucherdisease.org/treatment.php. And a listing of current clinical trials can be accessed here: https://www.gaucherdisease.org/research/current-research-protocols/.

This information was developed by the National Gaucher Foundation, Inc. and is herewith used with permission.

National Gaucher Foundation, Inc. Gaucher Disease. Available at: https://www.gaucherdisease.org/what-is-gaucher-disease.php. Accessed January 20, 2014.

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