HLA-DR4 allele and haplotype diversity in a hematopoietic cell transplant population

HLA class I null alleles and new alleles affect unrelated bone marrow donor searches

“…We found these three expression variants in a population of 2624 BMT patients and potential donors, who we routinely type by both serology and PCR‐SSP for an overall incidence of 0.11% and an incidence of 0.08% for null alleles. Smith et al found seven ‘null’ alleles in 10,000 HLA haplotypes identified by family studies (2). Hammond et al found four new ‘null’ alleles in 6000 Welsh bone marrow donors (unpublished, see reference material for AJ532608 ).…”

“… Abstract: Unrecognized HLA null alleles or new alleles may affect the outcome of bone marrow transplants using unrelated donors. Some reports suggest that null alleles occur in the range of 0.003–0.07% (1, 2), which has led some transplant programs to stop performing serologic typing. We describe nine cases involving expression variants or new alleles.…”

A nonsense mutation in Exon 3 results in the HLA‐B null allele B*5127N

“…The allele frequency of B*5127N is presently unknown as it has been identified in only one family to date. Another study indicates that several of the class I null alleles are present in populations at allele frequencies of approximately one per thousand (18). It is conceivable that many of the mutations that cause null alleles are spontaneous rather than inherited.…”

Characterization of two novel HLA‐A null alleles: A*11:210N and A*26:107N

“…Few studies have addressed systematically the frequency of null alleles in the population. Some publications have obtained a frequency between 0.003% and 0.08% for HLA null alleles . Only two non‐expressed alleles, A*02:53N and C*04:09N , have been defined as common alleles because their frequencies, in some populations, are higher than 0.001% .…”