Recent studies published on the genetic basis of ankylosing spondylitis (AS) reflect novel areas of investigation and extension of recent advances. As HLA-B27 subtypes have been extensively examined in other ethnic groups, novel insights into the relevance of HLA-B27 folding to disease susceptibility have led to questions regarding the influence of HLA-B27 on AS pathogenesis. The recent identification of IL23R, ERAP1, and interleukin-1 (IL1A) region genes in AS pathogenesis has led to a number of replication studies. Other genes with inconsistent AS associations (eg, KIR, TLR4, ANKH, and TNAP) have been further examined with inconsistent results. Potential candidate genes (TIRAP, COL1A6, and MEFV) have been examined with no associations found. Tremendous progress has been made with respect to understanding the genetic basis of AS. The identification of new genes-ARTS1, IL23R, and IL1A-substantiate that susceptibility to AS is also determined by genes outside the MHC.