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Genetic marker found for severe ulcerative colitis
By Bijal P. Trivedi

Ulcerative colitis (UC) is a chronic disease of the large intestine that leads to bloody diarrhea, abdominal cramps and fever. While no one knows exactly what causes the inflammation and ulcers, researchers do know that an overactive immune system and heredity are part of the equation. Now a team of scientists in Madrid, Spain, has found a genetic marker that they think might increase susceptibility to severe UC.

A study of 155 patients and 298 controls revealed a variant of the IKBL (inhibitor of kB-like) gene that was present in patients with severe UC. In this variant, the thymine (T) at position 738 of the IKBL gene is replaced with cytosine (C). The T to C switch causes an amino acid substitution of cysteine with arginine in the final protein. How this amino acid change alters the function of the IKBL protein is not known.

The IKBL gene is part of the MHC complex, a group of genes that play an essential role in defending the body. The researchers state in their report that they cannot determine from the current study whether the +738(C) variant of the IKBL is actually the gene responsible for increasing the severity of this disease, or whether it is a marker for a nearby gene that is exerting the effect. In either case, it may still prove an effective marker for identifying people at risk for the more dangerous form of the disease.

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De La Concha, E. G. et al. Susceptibility to severe ulcerative colitis is associated with polymorphism in the central MHC gene IKBL. Gastroenterology 119, 1491-1495 (December 2000).

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