FVIII sequence variants encoded by F8 ns-SNPs and haplotypes. (A) Schematic illustration of the FVIII protein, which consists of domains A1, A2, B, A3, C1, and C2. The F8 regions a1, a2, and ap are short stretches of acidic residues. The locations of 3 ns-SNPs encoding amino acid variations found in African and African American populations are indicated. (B) FVIII variants corresponding to 6 human haplotypes found in whites (primarily H1 and H2) and African Americans (primarily H1-H5). Haplotype H6 was found in an Asian subject of an earlier study.¹³  Shaded boxes indicate amino acid variants (single-letter code) that are not present in currently available recombinant FVIII products).