HLA genetic diversity in Hungarians and Hungarian Gypsies: complementary differentiation patterns and demographic signals revealed by HLA-A, -B and -DRB1 in Central Europe

Systematic analyses of human leukocyte antigen (HLA) profiles in different populations may increase the efficiency of bone marrow donor selection and help reconstructing human peopling history. We typed HLA-A, -B, and -DRB1 allele groups in two bone marrow donor cohorts of 2402 Hungarians and 186 Hungarian Gypsies and compared them with several Central-European, Spanish Gypsy, and Indian populations. Our results indicate that different European Gypsy populations share a common origin but diverged genetically as a consequence of founder effect and rapid genetic drift, whereas other European populations are related genetically in relation to geography. This study also suggests that while HLA-A accurately depicts the effects of genetic drift, HLA-B, and -DRB1 conserve more signatures of ancient population relationships, as a result of balancing selection.

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

The presence of null alleles may affect the outcome of stem cell transplantation. HLA-C*04:09N 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*02:01/A*23:01-B*44:03-DRB1*07:01-DQB1*02:01. We aimed to investigate HLA-C*04:09N in a representative Hungarian cohort. HLA-typing data of 7345 unrelated persons were analyzed. The presence of HLA-C*04:09N was excluded in 157 chromosomes with either serology typing or with an allele-specific polymerase chain reaction for HLA-C*04:09N. HLA-C*04:09N was identified in a single chromosome with HLA-A*02, B*44, C*04, DRB1*07 resulting in a HLA-C*04:09N 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.