About Gaucher Disease
Type 2 Gaucher Disease
Type 2 Gaucher disease is the rare acute neurological form of Gaucher disease, which accounts for approximately 5% of all Gaucher disease patients. The prevalence of type 2 Gaucher disease is almost zero because most type 2 patients do not live past the age of 2 years. It is characterized by severe neurological involvement of the brainstem that is associated with enlargement of internal abdominal organs. The first signs and symptoms occur around 3 to 6 months of age, which include:
- Oculomotor paralysis: infants have difficulty with normal eye movements and may appear cross-eyed
- Severe swallowing difficulty
- Increasing spasticity
- Difficulty with normal movements
- Myoclonic epilepsy: seizures
Type 2 Gaucher disease is a lysosomal storage disease caused by a mutation in the GBA gene on chromosome 1q21. This gene codes for glucocerebrosidase, which is a lysosomal enzyme. Enzymes are proteins that catalyze chemical reactions of other substances. Glucocerebrosidase helps cleave glucose from glucocerebrosides. Therefore, when there is a deficiency in glucocerebrosidase, there will be an accumulation of glucosylceramide in gaucher cells of the liver, spleen and bone marrow. Diagnosis of Gaucher disease can be confirmed by demonstrating a cellular deficiency in glucocerebrosidase enzyme activity.
Type 2 patients do not survive long enough to display signs and symptoms associated with Type 1 and 3 Gaucher disease. Treatments used for Gaucher type 1 and 3 have not been shown to have an effect on neurological symptoms associated with type 2 Gaucher disease, as exogenously administered enzyme does not cross the blood-brain barrier. If a patient has a family history or has already lost a child to type 2 Gaucher disease, a prenatal diagnosis can be done by measuring the enzyme activity between 10 and 12 weeks of pregnancy.