- A haploidentical donor that shares one haplotype in common with the recipient such that HLA compatibility will be a minimum of 5 out of 10 HLA loci matched. The HLA loci to be tested will be HLA A, B, Cw, DRB1, and DQB1. A minimum number of mismatches is desirable; however if several options are available the selection of a donor will be based on the loci where the mismatch occurs and the relative importance of its potential immunological function. Donor-recipient pairs will initially be typed molecularly to provide a low resolution typing (antigen-level) to aid in the selection of the potential donor. Upon review of the familial inheritance pattern, a qualified HLA staff member will review haplotype inheritance. High resolution (allele-level) typing will be performed. Final selection of a donor will be in consultation with NCI physicians and qualified HLA personnel. Haploidentical related donors for pediatric recipients must be 15 years of age or older. If more than one haploidentical related donor is available, we will evaluate each donor individually according to overall health, ABO matching, cytomegalovirus (CMV), etc. to select the donor