over a long period of time (e.g., bone marrow registry, cord blood bank). Inclusion of these data are key to prevent the data from being outdated, to provide a list of genotypes for future matching strategies, and to facilitate the search for rare/newer alleles. This is often key for patients with uncommon alleles who do not have many potential donors. In these situations, tools to facilitate the selection of donors with the greatest potential to carry the rare allele are essential to save time and conserve resources.

Correlation of DNA-Based and Serologic Types

Although a single serologic specificity was once thought to define the product of a single HLA allele, we now know that a single serologic specificity is associated with multiple allelic products (Table F-4) (73). For example, the serologic type HLA-A2 is found on over 60 different allelic products. Today, many cells carrying newly described alleles have not been rigorously serologically tested and a neural network approach has been used to predict the serologic assignments (48). Also, because the typing method is predominantly by DNA based methods, allelic products encoding apparently unique serologic specificities are not assigned new serologic specificities.

The nomenclature used to assign DNA-based HLA types is based on that used in serology; however, there are many examples where the assignments applied to an allele and to its product appear to differ from one another (for example, a protein with a B62 serologic determinant is encoded by the allele B*1501). These differences are often the result of the complex nature of serologic testing and the nomenclature system used to assign allele names. In addition, some allelic products carry new combina-

TABLE F-4 Examples of Alleles Which Encode Specific HLA Proteins (or Antigens)

Serologic Assignment

Allelic Products Which Carry Serologic Typea

A2

A*0201, A*0202, A*0203, A*0204, A*0205, A*0206, etc.

B7

B*0702, B*0703, B*0704, B*0705, B*0706, B*0707, etc.

B62

B*1501, B*1504, B*1505, B*1506, B*1507, B*1520, etc.

None assigned

B*8301

DR3

DRB1*0301, DRB1*0302, DRB1*0303, DRB1*0304, etc.

aNot all alleles in the group encode the antigen. For example, some of the A*02 alleles, e.g., A*0215N and A*0232N, do not encode a protein product. For example, not all alleles with names beginning B*15 encode proteins with the B62 serologic type. Other alleles in this group encode B63, B71, B72, B75, B76, B77 antigens.



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