Rheumatoid arthritis (RA) is a common auto-immune disease and about 1% of people are affected by RA (http://en.wikipedia.org/wiki/Rheumatoid_arthritis). Recent study suggested that about 1000 SNPs will explain big amount of genetic risk of RA (http://www.ncbi.nlm.nih.gov/pubmed?term=22446960). For more accurate genetic prediction, combination of SNPs will need to further investigate.
