There are almost 500 naturally occurring variants of hemoglobin. Most are the result of a single amino acid substitution in a globin polypeptide chain. Some variants produce clinical illness, though not all variants have deleterious effects. Identify the variant or variants that can be described by each of the three statements by placing the letter corresponding to the statement next to the variant. Statement B may describe more than one variant, and a variant may be described by more than one statement. At least one variant will not match any description. A. The Hb variant least likely to cause pathological symptoms. B. The variants most likely to show pI values different from that of HbA on an isoelectric focusing gel. C. The variant most likely to show a decrease in BPG binding and an increase in overall affinity for oxygen.