Antigens in the SC blood group system are expressed by the human erythrocyte membrane-associated protein (ERMAP). Two molecular bases have been reported for the Scnullphenotype: SC*307del2and SC*994C>T.We report our investigation of the molecular background of five Scnullindividuals from the Pacific Islands and describe the successful transfusion of Sc3+ blood to a patient with anti-Sc3 in her plasma. SC (ERMAP)exons 2, 3, and 12 and their flanking intronic regions were analyzed. The SC*994C>Tchange introduces a restriction enzyme cleavage site for Tsp45I, and polymerase chain reaction (PCR) products from exon 12 were subjected to this PCR–restriction fragment length polymorphism (RFLP) assay. The five samples had the variant SC*994T/T.One sample, from a first cousin of one Marshallese proband, was heterozygous for SC*1514C/T(in the 3′ untranslated region); the other four samples were SC*1514C/C(consensus sequence). Samples from white donors (n = 100) and African American donors (n = 99) were tested using the Tsp45I PCR-RFLP assay; all gave a banding pattern that was consistent with the SC*994C/Cconsensus sequence. In all five samples, our analyses showed homozygosity for the nonsense nucleotide change SC*994C>Tin an allele carrying the nucleotide associated with Sc1. Further investigation determined that one of the probands reported previously with the SC*994C>Tchange was from the Marshall Islands (which form part of the Micronesian Pacific Islands) and the other was from an unspecified location within the large collection of Pacific Islands. Taken together, the five known probands with the SC*994C>Tsilencing nucleotide change were from the Pacific Islands. Immunohematology2013;29:69–72.
