Allelic analysis showed that DRB1*0405, DRB1*0410, DQA1*03, DQB1*0401, and DQB1*0402 are positively associated and DRB1*1501, DRB1*1302, and DQB1*0602 negatively associated with Crohn's disease.
A total of 25 families with multiple cases of Crohn disease was genotyped for HLA DRB1 and for 16 highly polymorphic loci evenly distributed on chromosome 6.