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#24
PCR-SSP TYPING OF AN APPARENTLY HOMOZYGOUS A31 INDIVIDUAL REVEALS THE SEROLOGICALLY UNDETECTED HLA-A*2411N ALLELE.
Robin Medis , Melissa Marlowe , Rosalinda Partel , Evelyn Tomines , Paula Wetzsteon , Peter Curtin MD , Richard Maziarz MD , Douglas Norman MD and Robert O. Endres, PhD . Tempe AZ, Blood Systems Laboratories, HLA Laboratory and Portland OR, Oregon Health & Science University, Center for Hematologic Malignancies .

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A peripheral blood sample from a patient needing hematopoietic stem cell transplantation was submitted to our laboratory for HLA Class I and Class II high resolution typing. The individual had been serologically typed for HLA Class I as HLA-A31, blank; B44, B62 and DNA typed at low resolution for Class II alleles. Confirmation of the apparently homozygous A locus was performed using intermediate resolution Class I testing by PCR-SSP. It confirmed the presence of A*31, but also demonstrated A*24. Supplemental high resolution PCR-SSP testing yielded the result A*310102, A*2411N. The presence of the null A*2411N allele was confirmed using SSP kits from two different manufacturers. From comparison of results with two siblings, the projected genotype was: A*310102, Cw*0303, B*1501, DRB1*0101, DQB1*0501 / A*2411N, Cw*0501, B*4402, DRB1*0401, DRB4*0103, DQB1*0301. The combination of serological and molecular typing results for this case provides confirmation of the lack of expression of an allele that contains a frame shift insertion in the fourth exon. The conservative approach of confirming homozygous results and the use of molecular methodology continues to improve patient phenotyping.