Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
For each common C4 allele and HLA gene, the allele with strongest LD (r2) is listed if present on more than half of the haplotypes with that C4 allele (for 36,528 European ancestry and 14,804 African American haplotypes separately, with exact fraction as a percentage). r2 values greater than 0.4 are highlighted to point out particularly strong C4-HLA allele correlations, such as for several HLA alleles with the C4-B(S) allele in European ancestry individuals. Some common C4 alleles are further subdivided into distinct haplotypes used in imputation (and in Fig. 1b), as defined by shared alleles from variants flanking C4. Note that some alleles such as C4-A(L)-A(L)-3 are present at a low frequency in African Americans that might reflect their presence on admixed European-origin haplotypes spanning this region, whereas others such as C4-B(S) are likely to also exist on African haplotypes – these differences between C4 alleles are also reflected in the similarity of LD with HLA alleles to the corresponding row of the European ancestry section.