The transgene contains the human FCGR2A gene. The genomic clone used in the transgene encodes the R131 polymorphic form of human FcgRIIA, which binds the widest range of mouse IgG subclasses including mouse IgG1 and rat IgG2a as well. 10 copies of the transgene was estimated to have inserted into the genome. Transgenic mice express human FCGR2A on mouse platelets and macrophages at levels equivalent to that observed in human cells.