Gaucher disease
Gaucher disease, rare inherited metabolic disorder characterized by anemia, mental and neurologic impairment, yellowish pigmentation of the skin, enlargement of the spleen, and bone deterioration resulting in pathological fractures. Gaucher disease was initially described in 1882 by French physician Philippe Charles Ernest Gaucher. Gaucher disease is inherited as an autosomal recessive trait and is caused by one or more mutations in a gene called acid beta-glucosidase (GBA). These mutations result in defects in the synthesis of an enzyme called glucocerebrosidase, leading to the accumulation of lipids called glucocerebrosides in Gaucher cells. Gaucher cells are large, wrinkled-appearing cells that store glycolipids and are usually found in the bone marrow and the spleen.
There are three distinct forms of Gaucher disease: type 1, which can occur in childhood or adulthood; type 2, which occurs in infants; and type 3, which occurs in early childhood (sometimes called the Norrbottnian type). Type 1 is by far the most common form of Gaucher disease and has an especially high incidence among Ashkenazic Jews (ranging from 1 in 500 to 1 in 1,000 births). Its chief symptoms are an enlarged spleen and erosion of the long bones. These symptoms are often mild in effect, and the life span of persons afflicted with type 1 is only slightly reduced on average. Type 2 Gaucher disease is an acute form that primarily affects the central nervous system in the first years of life, resulting in enlargement of the spleen and liver, erosion of the long bones, and progressive mental retardation, muscle dysfunction, and seizures; death from respiratory failure usually occurs in early childhood. Type 3 also affects the central nervous system but develops more slowly and is therefore considered a chronic form of Gaucher disease. Individuals affected by type 3 may survive until early adulthood. In addition, there exists a rare cardiovascular form of Gaucher disease (sometimes called Gaucher-like disease) that is characterized by cardiovascular calcification (hardening) and neurological dysfunction of the eye (oculomotor apraxia).
Individuals affected by type 2 or type 3 Gaucher disease, as well as some individuals who carry genetic mutations associated with Gaucher disease, may develop parkinsonism or Parkinson disease (see nervous system disease: Diseases and disorders). While the connection between Gaucher disease and Parkinson disease is unclear, researchers have postulated that the accumulation of lipids in the central nervous system that occurs in patients with Gaucher disease may cause damage to dopaminergic neurons in the brain that leads to the development of Parkinson disease.
Type 1 Gaucher disease may be treated by enzyme replacement therapy in which injections of imiglucerase, a synthetic analog of glucocerebrosidase that is made using recombinant DNA technology, are administered on a weekly or biweekly basis. Enzyme replacement therapy is generally ineffective in treating type 2 and type 3 Gaucher disease, because the molecules of imiglucerase are large and therefore cannot cross the blood-brain barrier to enter the central nervous system to treat neurological symptoms. In addition, some people develop immune reactions to imiglucerase that are severe and result in the discontinuation of enzyme replacement therapy. Adults with type 1 Gaucher disease that cannot be treated with imiglucerase may instead be treated with miglustat, a drug taken orally that inhibits the production of glucocerebrosides. Treatments that may be considered for patients with type 2 or type 3 Gaucher disease, or when enzyme replacement therapy is not an option for patients with type 1, include splenectomy (removal of the spleen), blood transfusion, and bone marrow transplantation. Therapies aimed at managing other symptoms of Gaucher disease include analgesics (to relieve pain) and bisphosphonates (to prevent bone loss).