Frequency of HLA Alleles in a Mestizo Population: A Comparison between North-East and Central and South Mexico

Abstract

IntroductionHuman immune recognition of self and foreign is partially controlled by a set of genes in the Human Leukocyte Antigen complex (HLA). HLA is used to assure compatibility between donor and recipient for hematopoietic stem cells transplantation (HSCT). There are six "classical" HLA genes encoding highly polymorphic loci: HLA-A, B and C (Class I major histocompatibility complex), and HLA DR, DQ and DP (Class II). HLA is the most polymorphic region in human genome.ObjectivesTo quantify the frequency of HLA A, B, C, DRB1 and DQB1 alleles in our center, and to compare alleles previously reported in Central and South Mexico.MethodsDescriptive and retrospective data of HLA typing by PCR-SSP for class I and II HLA from January 2003 to September 2017 in our Institution were analyzed. Data obtained was compared with previously reported literature from Central and South Mexico by principal component analysis.ResultsHLA-A, B, C, DRB1 and DQB1 typing was performed in 1614 individuals between 2003 and 2017. The number of haplotypes found was 726. The most common combination was A*02,B*35,C*04,DRB1*08,DQB1*04, observed 38 times (5.2%). Table 1. The most frequent HLA alleles were HLA-A2 and HLA-DQ 03 with a frequency of 0.2961 and 0.2758, respectively. Table 2 The two groups compared (North-east and south Mexico) accounted for 100% of the total variation in the sample. Graph 1ConclusionsIn our country, performing matched unrelated and umbilical cord blood HSCT is difficult given the great variability in Mestizo populations between regions. Hispanics represent a small proportion of donors in established international registries. Therefore, haploidentical transplantation with post-transplant cyclophosphamide should be considered as an alternative donor source for HSCT as it increases donor availability at an affordable cost. Human immune recognition of self and foreign is partially controlled by a set of genes in the Human Leukocyte Antigen complex (HLA). HLA is used to assure compatibility between donor and recipient for hematopoietic stem cells transplantation (HSCT). There are six "classical" HLA genes encoding highly polymorphic loci: HLA-A, B and C (Class I major histocompatibility complex), and HLA DR, DQ and DP (Class II). HLA is the most polymorphic region in human genome. To quantify the frequency of HLA A, B, C, DRB1 and DQB1 alleles in our center, and to compare alleles previously reported in Central and South Mexico. Descriptive and retrospective data of HLA typing by PCR-SSP for class I and II HLA from January 2003 to September 2017 in our Institution were analyzed. Data obtained was compared with previously reported literature from Central and South Mexico by principal component analysis. HLA-A, B, C, DRB1 and DQB1 typing was performed in 1614 individuals between 2003 and 2017. The number of haplotypes found was 726. The most common combination was A*02,B*35,C*04,DRB1*08,DQB1*04, observed 38 times (5.2%). Table 1. The most frequent HLA alleles were HLA-A2 and HLA-DQ 03 with a frequency of 0.2961 and 0.2758, respectively. Table 2 The two groups compared (North-east and south Mexico) accounted for 100% of the total variation in the sample. Graph 1 In our country, performing matched unrelated and umbilical cord blood HSCT is difficult given the great variability in Mestizo populations between regions. Hispanics represent a small proportion of donors in established international registries. Therefore, haploidentical transplantation with post-transplant cyclophosphamide should be considered as an alternative donor source for HSCT as it increases donor availability at an affordable cost.