FRIDAY, April 4 (HealthDay News) -- Researchers have identified new genetic markers for Crohn's disease and ulcerative colitis in a study they say provides further evidence that people of Ashkenazi Jewish descent are more likely to develop the conditions.

Up to 30 percent of people in the United States with inflammatory bowel disease (IBD) have a family history of the condition, and about 25 percent of those families have histories of both Crohn's and ulcerative colitis, according to background information in this multi-center American and Canadian study. People of Ashkenazi Jewish (eastern European) descent are at least twice as likely to develop a form of IBD and are more likely to have a family history of IBD.

Crohn's is most frequently characterized by inflammation of the final section of the small bowel and parts of the colon, while ulcerative colitis involves inflammation of the internal lining of the rectum and colon.

In this study, researchers looked for DNA variations called single nucleotide polymorphisms (SNPs) in 993 families (244 of whom were Ashkenazi Jews) with Crohn's and ulcerative colitis.

Among those of Ashkenazi Jewish descent, the researchers found evidence of genetic markers for familial Crohn's disease on previously identified areas of chromosomes 1 and 3. They also pinpointed a previously unidentified region of chromosome 13 in both Jewish and non-Jewish families with Crohn's.

The researchers also identified areas on chromosomes 2 and 19 that may be related to ulcerative colitis in both groups.

The findings were published in the March issue of Genes and Immunity.

Until now, no gene regions implicated in IBD were specific to Ashkenazi Jews, and there was no genetic evidence to explain why they were twice as likely to develop the disorder, said study senor author Dr. Steven R. Brant, a gastroenterologist at Johns Hopkins.

"This increased risk for some Jewish people makes our study and results especially significant, since this is the first sample size of Jewish families, 244, that was large enough to identify novel gene regions for familial predisposition in this ethnic group," Brant said in a prepared statement.

More information

The American Academy of Family Physicians has more about IBD.