To the Editor,

I read the interesting manuscript by Lin et al. which provided a review on association of HLA-B27 with ankylosing spondylitis (AS) and clinical features of AS in different HLA-B27 subtypes [1]. I hereby draw your attention that some relevant articles have been missed from this review, and consequently, the results may be affected [2,3,4]. For example, current meta-analysis demonstrated the association of AS with HLA-B27, HLA-B27*02, and HLA-B27*04. However, in a study on 163 patients with AS in Iran, HLA-B27*05 and then HLA-B27*02 were the most prevalent HLA-B*27 subtypes. Conversely, HLA-B7*04 and HLA-B*2707 were rarely seen [2]. Moreover, literature review indicates that HLA-B27 subtypes are heterogeneous in various races and ethnicities entire the world. Therefore, it is logical that clinical features of AS associated with HLA-B27 subtypes are dissimilar in various parts of the world with different races and ethnicities. Therefore, the results of this analysis should not be generalized to all patients with AS. Clinical features of patients with AS with different HLA-B27 subtypes are suggested to be reviewed and meta-analyzed separately in various races and parts of the world. Research reviews on different races and regions of the world individually (like Europe, Middle East, Far East, and Africa) may help to exploring more exactly the association between symptoms and HLA-B27 subtypes in AS disease.