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#25
RECENTLY DESCRIBED Cw*0718 ALLELE IS FREQUENTLY ASSOCIATED WITH B*5801.
Robert O. Endres, PhD , Melissa Marlowe , Robin Medis , Rosalinda Partel and Evelyn Tomines . Tempe AZ, Blood Systems Laboratories, 85282, HLA Laboratory .
A HLA-Cw*07 variant allele was encountered by testing DNA polymorphisms with PCR-SSP kits. A patient needing hematopoietic stem cell transplantation was typed and shown to have Cw*07 at low resolution. The Cw*07 allele was typed with two PCR-SSP kits from different manufacturers that gave discrepant results. One identified the Cw*0701 allele and the other identified the Cw*0706 allele. A single primer mix distinguished Cw*0706 (+) from Cw*0701 (-) in each of the two kits. The first linked nucleotide positions 985 (exon 5) and 1043 (exon 6). The second linked nucleotide positions 891 (exon 4) and 992 (exon 5). The first was positive and the second was negative. A matched unrelated donor (MUD) for this patient gave identical results with both kits. DNA specimens from the UCLA DNA Exchange that had been reported to contain Cw*0701 were retested. Some were identified by both kits as *0701, but #286 and #314 reacted the same way as this patient and MUD. The recently reported sequence of Cw*0718 accounts exactly for the reaction patterns in both kits. Whenever a subject is typed to have Cw*0701 with one kit, we routinely test with the second kit as well. Additional patients and MUDs have been found with the same variant PCR-SSP reaction pattern. All but one so far have been associated with B*5801. Cw*0718 appeared to be associated with B*5703 in one case. Cw*0718 has been seen in at least 3 racial groups to date: Caucasian, African American, and Hispanic. Since this variant was encountered, all individuals with B*5801 that also had Cw*07 have been typed at high resolution to have Cw*0718 and not Cw*0701. Additional testing of older DNA samples in our laboratory that were typed with B*5801 and Cw*0701 is currently underway.