Three clinical forms (phenotypes) of Gaucher's disease are recognized.

Type 1, the adult, non-neuronopathic type, is by far the most common. Patients in this group usually bruise easily and experience fatigue due to anemia, low blood platelets, enlargement of the liver and spleen, weakening of the skeleton, and in some instances, lung and kidney impairment. There are no signs of brain involvement. The onset of clinical manifestations may be early in life, or delayed until adulthood.

Type 2 is the infantile or acute neuronopathic type. In this form, liver and spleen enlargement are apparent by 3 months of age. In addition, there is extensive and progressive brain damage. These patients usually die by 2 years of age.

Type 3 is the juvenile or Norrbotten form, in which liver and spleen enlargement is variable, and signs of brain involvement such as seizures gradually become apparent. All of these patients exhibit a deficiency of an enzyme called glucocerebrosidase that catalyzes the first step in the biodegradation of glucocerebroside. Except for the brain, glucocerebroside arises mainly from the biodegradation of old red and white blood cells. In the brain, glucocerebroside arises from the turnover of complex lipids during brain development and the formation of the myelin sheath of nerves.