Response to: 'Questions on 'Sequencing of the MHC region defines HLA-DQA1 as the major genetic risk for seropositive rheumatoid arthritis in Han Chinese population' by Guo et al' by Regueiro and Gonzalez

We appreciate Dr Gonzalez’s interest and comments on our recent publication ‘Sequencing of the major histocompatibility complex (MHC) region defines human leukocyte antigen (HLA)-DQA1 as the major genetic risk for seropositive rheumatoid arthritis in Han Chinese population’.1 2 Dr Gonzalez’s comments provide us with an opportunity to clarify and discuss the frequencies of amino-acids at position DQα1:160 and the protective association of DRβ1:37N in rheumatoid arthritis (RA), and to improve our study.\n\nOne of the concerns Dr Gonzalez expressed is the frequencies of three amino-acids (Asp (D), Ala (A) and Ser (S)) at DQα1:160 do not sum up to 1.0, that is, 0.20, 0.22 and ≈0.02 in controls; 0.36, 0.37 and ≈0.01 in RA patients. The explanation is that the ‘minor frequencies’ was set as default …