PURPOSE OF REVIEW: To review recent progress in the genetics of rheumatoid 
arthritis (RA) and discuss the implications for understanding the pathogenesis 
of the disease as well as clinical application.
RECENT FINDINGS: Protection against anticitrullinated protein antibody (ACPA) 
positive RA was shown to be associated wit DRB1*1301. Genome-wide association 
studies (GWASs) added about 10 new loci to the list of already more than 20 loci 
associated with RA, so the list is now over 30. Typing for the known risk loci 
is not helpful for prediction of the risk for RA. It is remarkable how few 
functional studies have been published.
SUMMARY: Known genetic factors explain 50-60% of the genetic variance for 
susceptibility to ACPA-positive and 30-50% for ACPA-negative RA. Searching for 
the remaining missing or hidden heritability is in all probability not going to 
yield much for prediction and/or targeted intervention. Therefore, I conclude 
that if you want to find more genes you should have a lot of patience, time and 
money, stop with convential GWAS and invest in large-scale sequencing of 
selected patients and controls. I have a better suggestion, however: use the 
information that is already available to perform functional studies in order to 
understand the mechanism of the known associations!