This variant is found in many inbred strains including C57BL/6J, C58/J, AKR/J, SJL/J, SWR. Sequence analysis shows that relative to the a variant of C3H/HeJ the b variant has point mutations that result in isoleucine instead of valine at amino acid 9, glutamine instead of leucine at amino acid 52, and phenylalanine instead of isoleucine at amino acid 71, all within the amino terminal scavenger receptor cysteine-rich D1 domain, in addition to 7 silent point mutations.