NMDP database, DRB1*11AD is used. AD is a code specifying 01 or 04. Many volunteer donors on registries are typed at this level of resolution.

High Resolution Level

DNA-based typing identifies the specific allele carried by an individual (e.g., DRB1*1104) or may narrow down the possibilities to one highly likely allele and one to several rare alleles (e.g., A*0201 or A*0209 or A*0243N). This level of typing is not routinely carried out during the typing of new volunteers because of the cost and manpower involved. High-resolution testing is frequently carried out by the transplant center to determine the degree of the HLA match between a patient and a specific potential donor.

Allele Level

DNA-based typing identifies the specific allele carried by an individual (e.g., DRB1*1104). This level of typing is not routinely carried out during the typing of new volunteers because of the cost and manpower involved. High resolution testing is frequently carried out by the transplant center to determine the degree of the HLA match between a patient and a specific potential donor.

Cost of Typing

The cost of typing varies depending, in part, on the method, reagents, resolution, and volume of testing. For clinical HLA typing laboratories performing high numbers of new volunteer donor typing for a registry, the approximate cost is $55 to assign intermediate assignments at three loci (A, B, DRB1). (Price does not include phlebotomy.) For testing of 5 loci (A, B, C, DRB1, DQB1) at allele resolution in a laboratory performing large-volume testing, the assay may cost approximately $800–$1000. The cost will be higher in laboratories that perform testing on a smaller scale, for example, only for their own hospital.

Impact of Allele Discovery and Genotype Summarization on Test Interpretation

Approximately two new HLA alleles are reported each week (50). With the continued increase in the number of known HLA alleles, primary HLA testing data (nucleotide polymorphisms detected as present or absent) should be obtained and stored in addition to interpreted assignments (26, 27, 28, 49). This is particularly important for typing data which is used



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