tokens: These studies suggest that the genes for Factor B and C2 deficiency are located outside those for HLA , that the order of genese is HLA - A , - B , - D , Factor B allotype , C2 deficiency , that the genes coding for C2 deficiency and Factor B allotypes are approximately 3 - - 5 centimorgans from the HLA - A and HLA - B loci , and that the apparent lack of recombinants between the Factor B gene and C2 deficiency gene suggests that these two genes lie in close proximity to one another .