Both genetic and environmental factors affect susceptibility, severity and 
probably drugs' efficacy in patients with rheumatoid arthritis (RA). After 
initial completion of the Human Genome Project on the 16th February 2001, 
significant progress has been made in identifying other than HLA genome regions 
linked to the increased RA susceptibility. As an effect several new genes have 
been recognized as an HLA-independent genetic risk factors of RA. PTPN22 gene 
polymorphism, C5/TRAF1 genes region polymorphism and TNFAIP3-OLIG3 genes region 
polymorphism(s) are among newly identified and already confirmed genetic risk 
factors, whereas STAT 4, CTLA4, PADI4 and IRF5 genes polymorphisms are listed 
among probable RA development genetic risk factors.