Chances of finding an HLA-matched sibling: The Saudi experience.

Hematopoietic cell transplantation (HCT) remains the fundamental procedure to treat many diseases. Its success depends greatly on the degree of HLA matching between donor and recipient. Although the number of successful HCT procedures carried out worldwide increases every year, many patients remain unable to receive this treatment because of the difficulty of finding an HLA-matching donor. In our center, we identified the HLA types for all HCT candidates and their siblings in an attempt to determine the chance of finding a full HLA-matching sibling. Overall, 60% of patients had a chance of finding an HLA-matching sibling. The chance of finding a matching sibling was 43% in patients aged birth to 5 years, compared with 68% in those aged 20+ years. In our Saudi population, patients in need of HCT have a greater chance of finding an HLA-matching sibling than is reported in most Western countries. This is mainly because of the larger number of siblings in most Saudi families. Younger children requiring HCT have a lesser chance of finding an HLA-matching sibling. Our data demonstrate that even in a country with relatively large families, it is still essential to consider alternative donor strategies, such as adult unrelated donors, unrelated umbilical cord blood units, and haploidentical donors.

HLA-C polymorphisms in two cohorts of donors for bone marrow transplantation.

The typing for HLA-C in transplantation was rather neglected in the past. However, several recent studies have emphasized its role in transplantation and its association with the outcome. Serological typing of HLA-C could identify only a limited number of HLA-C antigens, resulting in a number of HLA-C blanks. This was mainly due to the low expression of surface HLA-C and the small number of available specific anti-sera. Performing molecular methods has identified new HLA-C alleles and filled the blank of most serological typed antigens. In this study, we compared serological and molecular typing of HLA-C in two cohorts of healthy Saudis. Our serological typing method identified HLA-C1-7 with different frequencies, 23.5% of the alleles were not identified and thus defined as blank. Using the SSP molecular method, all samples were typed and all alleles were defined. Both methods showed that C∗07 and C∗06 have the highest frequency in the Saudi population. Our study emphasizes the importance of molecular methods in identifying all possible HLA-C alleles.