1.2
#18
RECOMMENDATIONS FOR EXTENDED HISTOCOMPATIBILITY TESTING TO CONFIRM HLA "IDENTITY" FOR "MATCHED" SIBLING STEM CELL DONORS OR FOR CASES WITH KNOWN MISMATCHES.
Marilyn S. Pollack, Ph.D. and Laura M. McNeish, B.S. . San Antonio TX, University of Texas Health Science Center, 78229, Department of Pathology and San Antonio TX, University Health System, 78229, Histocompatibility and Immunogenetics Laboratory .

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Current ASHI standards and guidelines require that the HLA "identity" of a "matched" sibling stem cell donor be verified by a family study to determine genotypes, or MLC testing or high resolution class II typing to assess DR compatibility. However, most family studies are not complete enough to determine all possible alternative genotypes, and, in many cases, the possible genotypes found or deduced for the parents do not preclude the possibility for an undetected recombination (e.g., a parent who is known or deduced to be homozygous for DR4 at low resolution). In addition, recent studies have convincingly shown that allele level mismatches for A,B or C class I types or for DQ types that might not be detected by following the current ASHI guidelines can also significantly impact stem cell transplant outcome. The possibility for an undetected class I allele recombination, e.g. for a non-caucasian parent who is known or deduced to be homozygous for A2 at low resolution, should therefore also be considered. There are several examples of cases where specific class I allele level differences are likely to impact stem cell transplant outcome. Related potential donor case studies in which extended histocompatibility testing was undertaken and recommendations for general guidelines will be presented. The reasons for, and guidelines for, additional testing that should be performed when a selected potential donor has a known mismatch will also be presented.