Conservation of naturally occurring polymorphisms in Fcgr2b in congenic and wild mice. (A) Four deletions (X) have been identified within regulatory regions of the murine Fcgr2b gene, two in the promoter and two in intron 3. These deletions form three haplotypes in inbred strains of mice. The core promoters of Fcgr2b from the NZB (haplotype I), NZW (haplotype II), and C57BL/6 (haplotype III) strains were aligned using ClustalW. Polymorphisms present only in the NZW strain are highlighted in purple, those present only in the NZB strain in green, and those present in both NZB and NZW in yellow. A predicted AP-1–binding site is indicated by a red box. The asterisks below the sequences represent sequence identity. (B) Distribution of Fcgr2b polymorphisms within the inbred strain genealogy generated by Beck et al. (2000). (C) Fcgr2b haplotypes in wild mice. 53 DNA samples were obtained from wild mice from around the world, and the Fcgr2b haplotype was determined. Each circle represents a separate DNA sample.