Type 1 Gaucher disease is a rare genetic disorder that results from a mutation in the gene that makes an enzyme called glucocerebrosidase. This mutation means your body produces less of the enzyme than it needs.

The job of glucocerebrosidase is to break down glucosylceramide, a fatty substrate. The enzyme mainly does its job in small compartments called lysosomes. Lysosomes are located inside cells called macrophages, cells that break down the majority of glucosylceramide in your body.

In people without type 1 Gaucher disease there is enough naturally occurring enzyme to break down all the glucosylceramide substrate and create a healthy balance. But in type 1 Gaucher disease there is a shortage of the enzyme, so the substrate is broken down more slowly. The extra substrate builds up in lysosomes, where it causes imbalance and macrophage enlargement (enlarged macrophages are called Gaucher cells). The buildup of glucosylceramide substrate has many consequences, such as liver and spleen enlargement, anemia, and low platelet count.