Fig. 1.

Index family in the characterization of the Sm antigen and demonstration of the antithetical relationship between Sm and Bu^a antigens. The proband (patient Ms. Scianna) is indicated by the arrow. Solid color represents Sm+ (Sc:1+) antigen test. Striped fill represents Bu^a+ (Sc:2+) antigen test. Inferred genotype is shown below the symbol for each family member. The proband’s parents were deceased at the time of Bu^a testing, so are inferred to be heterozygotes, indicated by the interrupted stripes and parentheses in their genotype designation. The combination of Sm and Bu^a typing confirms that subject AM is a heterozygote, which was suggested by observations of dosage effects in serologic testing. (Redrawn with data from references ² and ⁴.)