Abstract
A family from Opava, Czechoslovakia, with a Gc variant is described. The variant has an electrophoretic mobility between Gc 1–1 and Gc 2–2. The notation Gc Opava (Gc Op) is proposed. The variant appears to be determined by an allele at the Gc locus, GcOp. Three family members had the phenotype Gc Op‐1; three family members had the phenotype Gc Op‐2.