HLA typing is useful in-

Reference :Robbins basic pathology 9th edition pg no 117:As a result of the polymorphism at the major HLA loci in the population, a viually in nite number of combina- tions of molecules exist, and each person expresses a unique MHC antigenic pro le on his or her cells. The com- bination of HLA alleles for each person is called the HLA haplotype. The implications of HLA polymorphism are obvious in the context of transplantation--because each person has HLA alleles that differ to some extent from every other person's, grafts from viually any donor will evoke immune responses in the recipient and be rejected (except, of course, for identical twins). In fact, HLA mole- cules were discovered in the course of early attempts at tissue transplantation.