Krabbe disease is an inherited enzyme deficiency that leads to the loss of myelin, the substance that wraps nerve cells and speeds cell communication. Most affected individuals start to show symptoms before six months of age and have progressive loss of mental and motor function. Death occurs at an average age of 13 months. Other less common forms exist with onset in later childhood or adulthood.
Myelin insulates and protects the nerves in the central and peripheral nervous system. It is essential for efficient nerve cell communication (signals) and body functions such as walking, talking, coordination, and thinking. As nerves grow, myelin is constantly being built, broken down, recycled, and rebuilt. Enzymes break down, or metabolize, fats, carbohydrates, and proteins in the body including the components of myelin.
Individuals with Krabbe disease are lacking the enzyme galactosylceramidase (GALC), which metabolizes a myelin fat component called galactosylceramide and its by-product, psychosine. Without GALC, these substances are not metabolized and accumulate in large globoid cells. For this reason, Krabbe disease is also called globoid cell leukodystrophy. Accumulation of galactosylceramide and psychosine is toxic and leads to the loss of myelinproducing cells and myelin itself. This results in impaired nerve function and the gradual loss of developmental skills such as walking and talking.
Amie Stanley MS, Rosalyn Carson-DeWitt MD, The Gale Group Inc., Gale, Detroit,