Matilde Romero

HLA-DRB1 * 04 and DRB1 * 10 are associated with resistance and susceptibility, respectively, in Brazilian and Vietnamese leprosy patients

The host genetic background has been considered one of the factors that influence leprosy outcome, a chronic infectious disease caused by Mycobacterium leprae. Genome scans demonstrated that the 6p21 region is associated with leprosy and a substantial number of population-based studies analyzing human leukocyte antigen (HLA) class II loci suggested association of HLA-DR with leprosy. However, some studies lacked robustness as they had limited power. Indeed, experimental designs require increased sample size to achieve adequate power, as well as replication studies with independent samples for confirmation of previous findings. In this work, we analyzed the influence of the HLA-DRB1 locus on leprosy susceptibility per se and disease type using a case–control design carried out in Brazilians (578 cases and 691 controls) and a replication study based on a family design in a Vietnamese population (n=194 families). The results showed that HLA-DRB1*10 is associated with susceptibility to leprosy and HLA-DRB1*04 is associated with resistance, both in the Brazilian and Vietnamese populations suggesting that these alleles play an important role in the activation of cellular immune responses against M. leprae.

Analysis of the HLA population data (AHPD) submitted to the 15th International Histocompatibility/Immunogenetics Workshop by using the Gene[rate] computer tools accommodating ambiguous data (AHPD project report)

During the 15th International Histocompatibility and Immunogenetics Workshop (IHIWS), 14 human leukocyte antigen (HLA) laboratories participated in the Analysis of HLA Population Data (AHPD) project where 18 new population samples were analyzed statistically and compared with data available from previous workshops. To that aim, an original methodology was developed and used (i) to estimate frequencies by taking into account ambiguous genotypic data, (ii) to test for Hardy-Weinberg equilibrium (HWE) by using a nested likelihood ratio test involving a parameter accounting for HWE deviations, (iii) to test for selective neutrality by using a resampling algorithm, and (iv) to provide explicit graphical representations including allele frequencies and basic statistics for each series of data. A total of 66 data series (1-7 loci per population) were analyzed with this standard approach. Frequency estimates were compliant with HWE in all but one population of mixed stem cell donors. Neutrality testing confirmed the observation of heterozygote excess at all HLA loci, although a significant deviation was established in only a few cases. Population comparisons showed that HLA genetic patterns were mostly shaped by geographic and/or linguistic differentiations in Africa and Europe, but not in America where both genetic drift in isolated populations and gene flow in admixed populations led to a more complex genetic structure. Overall, a fruitful collaboration between HLA typing laboratories and population geneticists allowed finding useful solutions to the problem of estimating gene frequencies and testing basic population diversity statistics on highly complex HLA data (high numbers of alleles and ambiguities), with promising applications in either anthropological, epidemiological, or transplantation studies.

HLA in Brazilian Ashkenazic Jews with chronic dermatophytosis caused by Trichophyton rubrum

The frequency of HLA (Human Leucocyte Antigens) was analyzed in 25 non-consanguineous Brazilian Ashkenazic Jews, resident in the city of Sao Paulo, Brazil, suffering from chronic dermatophytosis caused by T. rubrum, and in 25 non-infected individuals belonging to the same ethnic group. Statistically significant values (p<0.05) were observed for HLA-B14 associated with resistance to chronic dermatophytosis and HLA-DQB1*06 (p=0.05) possibly related to susceptibility. These findings suggest that genes on the chromosome 6, in the region of the major histocompatibility complex, may influence the development of chronic dermatophytosis.

The distribution of HLA haplotypes in the ethnic groups that make up the Brazilian Bone Marrow Volunteer Donor Registry (REDOME)

The Registries of Bone Marrow Donors around the world include more than 30 million volunteer donors from 57 different countries, and were responsible for over 17,000 hematopoietic stem cell transplants in 2016. The Brazilian Bone Marrow Volunteer Donor Registry (REDOME) was established in 1993 and is the third largest registry in the world with more than 4.3 million donors. We characterized HLA allele and haplotypes frequencies from REDOME comparing them with the donor self-reported race group classification. Five-locus haplotype frequencies (A~C~B~DRB1~DQB1) were estimated for each of the six race groups, resolving phase and allelic ambiguity using the expectation–maximization (EM) algorithm. The top 100 haplotypes in the race groups were separated into eight clusters of haplotypes, based on haplotype similarity, using CLUTO. We present HLA allele and haplotype frequency data from six race groups from 2,938,259 individuals from REDOME. The most frequent haplotype was the same for all groups: A*01:01g~C*07:01g~B*08:01g~DRB1*03:01g~DQB1*02:01g. Some frequent haplotypes such as A*02:01g~C*16:01g~B*44:03~DRB1*07:01g~DQB1*02:01g was not found in people with Preta (Sub-Saharan African descent). A cluster including Branca (European) and Parda or non-informed (admixed) could be distinguished from both Preta (SubSaharan) and Indígena (Amerindian) groups, and from the Amarela (Asian) ones, which clustered with their original population. These results have implications on cross-population matching and can help in donor searches and population-based recruitment strategies.

92-P : UNUSUAL HLA-DRB1-DQA1-DQB1 ASSOCIATION FOUND IN AN EXTENDED HAPLOTYPE IN SEVEN BRAZILIAN INDIVIDUALS

Aim To report an unusual association of HLA-DRB1∗11:01- HLA-DQA1∗05:05-HLA-DQB1∗04:02 found in seven Brazilian individuals. Methods HLA analysis was performed in 14213 randomly selected individuals (7162 patients and 7051 normal donors) from Rio de Janeiro and Sao Paulo - Brazil. The great majority of the HLA typing was performed by intermediate resolution methodologies by polymerase chain reaction with sequence specific oligonucleotides (PCR-SSO) using commercial kits (Lab-Type SSO; One Lambda inc., Canoga Park , CA) and /or rSSO – InnoLiPA (Innogenetics, NV, Ghent, Belgium). High resolution typings were performed by PCR-SBT (AlleleSEQR-HLA-SBT Reagents, Celera, USA). Results In Brazilians, as reported in other ethnic groups, HLA-DRB1∗11 is found associated with different HLA-DQB1 alleles: HLA-DQB1∗02:01, 03:01, 03:02, 03:03, 03:04, 03:19, 05:01, 05:02, 06:02, 06:11 and 06:03. The most frequent association is HLA-DRB1∗11:01- HLA-DQB1∗03:01, mainly in Brazilian Caucasoid. An interesting, unusual and not yet reported HLA-DRB1∗11:01 association was found with HLA-DQA1∗05:05, HLA-DQB1∗04:02 in 4 of the patients and in 3 of the normal donors. This HLA-DRB1-DQA1-DQB1 association, shares an extended haplotype: HLA-A∗02:01, HLA-C∗14:02, HLA-B∗51:01, HLA-DRB1∗11:01, HLA-DQA1∗05:05, HLA-DQB1∗04:02. This data was confirmed by segregation analysis, performed in a parallel study, in one of these patient’s family. Conclusions The identification of this rare extended haplotype, shown here for the first time in Brazilians, and so far not reported in other populations, is a good example of our ethnic diversity and may be an important data to take into consideration for recruitment and matching process of unrelated donors for haematopoietic stem cell transplantation.