Krabbe disease is a rare genetic condition in which an abnormal accumulation of fat molecules called galactolipids affects the cells in the nervous system. In particular, Krabbe disease affects the cells which produce myelin — the substance that insulates and protects nerve cells. The disease, which is sometimes called globoid cell leukodystrophy or Krabbe’s leukodystrophy, is one of about 50 which are classified as lysosomal storage disorders (LSD), where a genetic variation disrupts the normal activity of lysosomes in human cells.