The second theory is that there are several different forms of both Crohn's disease and ulcerative colitis. In other words, IBD might encompass every possible inheritance pattern. The prospect of investigating these complicated scenarios may seem daunting. But, thanks to advances in the field of genetics, the great IBD gene search is gaining momentum. A genetic marker is a segment of DNA that has a distinctive, highly variable pattern.
Scientists now know the variations and locations of many genetic markers on each human chromosome.
They are using these markers in two kinds of studies. Let's look at an example. Researchers find that Paul and Joan Warren, a brother and sister who have Crohn's disease, carry the same genetic marker. Since neighboring segments of DNA tend to be linked and inherited together, disease genes are likely to reside close to the genetic markers that are co-inherited with IBD in families. On the other hand, this marker may be linked to a different Warren family trait, such as curly hair.