Abstract
Recombinant points are frequent in the human genome, where parts of homologous chromosomes are exchanged resulting in recombinant chromosomes. In the literature, several recombinant points have been reported in the HLA region. One of the previously reported common haplotype is HLA-A∗02, C∗06, B∗50, DRB1∗07, DQB1∗021. Saudi families are known to have very high consanguineous marriages2. They also have higher than expected homozygosity in the HLA genes3. The aim of this study was to determine the most frequent HLA haplotype among the donors of the Saudi Stem Cell Donor Registry (n=36670).
We analysed our Saudi registry’s HLA typing by listing all homozygous haplotypes.
Homozygosity of the haplotype HLA-A∗02, C∗06, B∗50, DRB1∗07, DQB1∗02 occurred in only 0.27% of our donors (99/36770). Furthermore, homozygosity of HLA-C∗06, B∗50, DRB1∗07, DQB1∗02 occurred in 1.1% of our donors (395/36770). This was also true for other frequent haplotypes such as HLA-A∗02, C∗07, B∗08, DRB1∗03, DQB1∗02. However, homozygosity of HLA-C∗07, B∗08, DRB1∗03, DQB1∗02, was much more frequent (0.39% or 144/36770), thus indirectly suggesting the presence of a hot recombinant point between HLA-A and HLA-C in the Saudi population.
The data presented here suggest that hot point between HLA-A and HLA-C may affect the chances of finding full HLA match in the local registry.