Crohn's disease after gastroenterologist Burrill Bernard Crohn, who, in 1932, together with two other colleagues at Mount Sinai Hospital in New York, described a series of patients with inflammation of the terminal ileum of the small intestine, the area most commonly affected by the illness. Many people with Crohn's disease have symptoms for years before the diagnosis. The usual onset is between 15 and 30 years of age, but can occur at any age. Because of the 'patchy' nature of the gastrointestinal disease and the depth of tissue involvement, initial symptoms can be more subtle than those of ulcerative colitis. People with
Krabbe disease may be caused by a lack of active saposin A (a derivative of prosaposin). The buildup of unmetabolized lipids adversely affects the growth of the nerve's protective myelin sheath (the covering that insulates many nerves) resulting in demyelination and severe progressive degeneration of motor skills. As part of a group of disorders known as leukodystrophies, Krabbe disease results from the imperfect growth and development of myelin. GALC deficiency also results in a build-up of a glycosphingolipid called psychosine, which is toxic to oligodendrocytes, a type of non-neuronal cell found in the nervous system, collectively termed neuroglia. The disease may be