Genetics of Crohn's Disease in African Americans

Association studies have previously identified 200 genome-wide significant (GWS) IBD susceptibility loci in European ancestry populations. At least thirty-five loci have been identified in Asians and a handful appear Asian specific. AAs have a higher risk for developing disease complications in IBD and worse disease outcome, suggesting that significant differences in pathological and molecular mechanisms may exist in AAs. It was therefore imperative to use more comprehensive genotyping platforms in more highly powered samples to detect AA-specific IBD loci and associations. We conducted two independent GWAS using a total of 2345 AA IBD cases and 5002 controls population from unrelated, self-identified AAs individuals. GWAS1 included 1258 IBD cases (843 CD, 368 UC, 47 IBD-U) and 1678 controls derived from the dbGaP Health and Retirement Study (phs000428). GWAS 2 included 1087 IBD cases (803 CD, 215 UC, 69 IBD-U) and 3324 controls obtained from the Kaiser RPGEH study (phs000788).]]>
Study InformationInclusion Criteria Males or females with or without IBD. Able to provide written informed consent. Exclusion Criteria Infectious colitis For minimal risk to study participants, blood draw volume must be limited to no more than 3 ml/kg of patient weight; therefore, patients weighing less than 3.4 kg (7.48 lbs) are excluded. Patients with acute life threatening illness or conditions will not be asked to participate. ]]>
Scant literature with small study series on Crohn's disease (CD) epidemiology and phenotypes exist on African Americans (AA). Although it is widely believed and accepted that the prevalence of CD is less common in people of African descent, emerging data have shown that the incidence of CD among AAs is the same as compared with Caucasians of European descent. Data on CD, the disease course and outcomes in AA is limited. Additionally, there is a complete absence of population based data in AA. Findings from greater Atlanta area (adult data -Emory, Grady and VA hospitals, pediatric data -Children's Health Care of Atlanta) suggest that CD is widespread among AA. According to the US Census, about ~15% of the US population self-identifies as African Americans. Crohn's disease is estimated to affect over 500,000 individuals in the US. Hence, by extrapolation, 55,000 (~15%) African-Americans suffer from CD.]]>