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.