Causes

Krabbe disease is caused when a person inherits two copies of an altered (mutated) gene — one copy from each parent.

A gene provides a kind of blueprint for producing proteins. If there is an error in this blueprint, then the protein product may not work properly. In the case of Krabbe disease, two mutated copies of a particular gene result in little or no production of an enzyme called galactocerebrosidase (GALC).

Enzymes, such as GALC, are responsible for breaking down certain substances in a cell's recycling center (lysosome). In Krabbe disease, the short supply of GALC enzymes results in the accumulation of certain types of fats called galactolipids.

Damage to nerve cells

Galactolipids normally exist in cells that produce and maintain the protective coating of nerve cells (myelin). However, an abundance of galactolipids has a toxic effect. Some galactolipids trigger myelin-forming cells to self-destruct.

Other galactolipids are taken up by specialized debris-eating cells in the nervous system called microglia. The process of cleaning up excessive galactolipids transforms these normally helpful cells into abnormal, toxic cells called globoid cells, which promote myelin-damaging inflammation.

The subsequent loss of myelin (demyelination) prevents nerve cells from sending and receiving messages.