Genetics in rheumatoid arthritis.

The data from the human genome project were published in 2001. Although this achievement will boost research in the genetics of rheumatoid arthritis (RA), most of the work is in progress. Three of the four consortia that are performing linkage studies to identify loci that are transmitted more often to patients than controls have published data on genome-wide searches in few families. Of all the possible candidate genes, the human leukocyte antigen (HLA) class II region was found in the pan-European and the US linkage studies, confirming the previous data from association studies that HLA class II alleles confer risk to RA. Although HLA as a risk factor for RA has been known for a long time, the mechanism by which HLA alleles affect disease risk are controversial. Several papers have been published recently that support the RA-protection hypothesis. Several candidate loci/genes have been suggested from association studies. However, these associations have not been reproduced by different groups in several different cohorts.