Gaucher disease type 1 (GD1) is the most common form of Gaucher disease. Like other types of Gaucher disease, GD1 is caused when not enough glucocerebrosidase (GBA) is made. GBA is an important enzyme that breaks down a fatty chemical called glucocerebroside. Because the body cannot break down this chemical, fat-filled Gaucher cells build up in areas like the spleen, liver and bone marrow. Unlike type 2 and 3, GD1 does not usually involve the brain and spinal cord (central nervous system). Symptoms of GD1 include enlarged spleen and liver, low blood cell counts, bleeding problems and bone disease. The symptoms can range from mild to severe and may appear anytime from childhood to adulthood. Gaucher disease is caused by changes in the GBA gene and is inherited in an autosomal recessive manner. Diagnosis is suspected by clinical symptoms and confirmed by measuring GBA enzyme activity or genetic testing.