Low occurrence of the HLA-C*04:09N allele in a large Hungarian cohort.

ABSTRACT

The presence of null alleles may affect the outcome of stem cell transplantation. HLA-C*0409N was defined as 'common' with a frequency of 2-5/1000 in Caucasians, and its presence is routinely tested as part of haplotypes HLA-A*0201/A*2301-B*4403-DRB1*0701-DQB1*0201. We aimed to investigate HLA-C*0409N in a representative Hungarian cohort. HLA-typing data of 7345 unrelated persons were analyzed. The presence of HLA-C*0409N was excluded in 157 chromosomes with either serology typing or with an allele-specific polymerase chain reaction for HLA-C*0409N. HLA-C*0409N was identified in a single chromosome with HLA-A*02, B*44, C*04, DRB1*07 resulting in a HLA-C*0409N allele frequency of 0.0068% (1/14,690). This is approximately a 10- to 40-fold lower frequency compared with the previous data. Our results emphasize the need of precise local population-specific HLA-data, allowing appropriate modifications of local HLA-typing protocols.