HLA-DR09 (DR9) is a HLA-DR serotype that recognizes the DRB1*1001 gene product.
The serological reaction of DR9 is relatively good. The serology of DRB1*0902 to *0906 serotypes is unknown.
DRB1*0901: Early childhood myastenia gravis
DRB1*0901:DQA1*0301:DQB1*0303 haplotype: Early childhood myastenia gravis
HLA-DR9 is genetically linked to HLA-DR53, and HLA-DQ3 and DQ9 serotypes.