[Implications of HLA linkage disequilibrium phenomenon in finding unrelated volunteer bone marrow donors]

The distribution of HLA genes and haplotypes in the normal population is of considerable importance in disease susceptability studies, population and genetic studies and tissue and organ transplantation. The HLA phenotype frequencies can be used for the estimation of the probability of finding phenotypically identical unrelated volunteer bone marrow donors. It has been presumed that patients with HLA haplotypes in strong linkage disequilibrium, a have higher probability of finding HLA identical unrelated donors than others.

HLA gene and haplotype frequencies were calculated, as well as delta values and their significance. The implications of HLA disequilibrium phenomenon in unrelated donor search, was investigated by calculating the correlation coefficient between frequencies of haplotypes showing significant delta values and the linkage disequilibrium coefficient, as well as between the average number of donors necessary for research.

Haplotypes showing the highest delta values are at the same time the most frequent haplotypes (A1B8:0,1188 and 0,145; A3B35:0,0722 and 0,1;A2B12:0,055 and 0,105). In patients who have both haplotypes showing significant delta values (e.g. A2B5/A3B35), the number of donors necessary for research is clearly lower than in patients who have only one given haplotype, or have no such haplotypes.

Our results showed that patients with HLA haplotypes showing significant delta values have a higher probability of finding HLA identical unrelated donors.