The present invention provides methods for predicting the likelihood of development of systemic lupus erythematosus (SLE) in an individual, which comprise determining the sequence at one or more polymorphic positions within the human genes encoding FcRIIB. The invention also provides isolated nucleic acids encoding FcRIIB polymorphisms, nucleic acid probes that hybridize to polymorphic positions and kits for the prediction of SLE status.