 Serological studies of DQ recognized that antibodies to DQ bind primarily to the β-chain.The currently used serotypes are HLA-DQ2, -DQ3, -DQ4, -DQ5, -DQ6, -DQ7, -DQ8, -DQ9.HLA-DQ1 is a weak reaction to the α-chain and was replaced by DQ5 and DQ6 serology.