People with two copies of a certain version of a receptor (R131) are more likely to get lupus because that version doesn’t grab onto certain antibodies as well, leading to poor clearance of immune complexes.

This study talks generally about how certain immune proteins might be involved in lupus, but it doesn’t mention the specific version of the protein (R131 vs. H131) or show that one binds IgG2 worse or causes more lupus.