Determination of HLA-A, -B, and -DRB1 Allele and Haplotype Frequencies in the Croatian Population Based on a Family Study

HLA Polymorphisms and Clinical Manifestations in IgA Vasculitis

Studies concerning the genetic background of IgA vasculitis (IgAV), a small-vessel vasculitis occurring predominantly in childhood, have confirmed that the HLA-DRB1 gene showed a strong association with disease susceptibility. The objective was to investigate human leukocyte antigen (HLA) polymorphisms among Croatian patients with IgAV and their influence on disease susceptibility and clinical heterogeneity. Thus, 130 children with IgAV and 202 unrelated healthy individuals were enrolled in the study. Genomic DNA was extracted from whole peripheral blood, and HLA-A, -B, -DRB1 and -DQB1 gene polymorphism analysis was performed. HLA-A*03 (21.4% vs. 12.38%, p = 0.0092), HLA-B*37 (2.9% vs. 0.2%, p = 0.0054) and HLA-DRB1*12 (3.1% vs. 0.7%, p = 0.0216) alleles were significantly more frequent in IgAV patients than in controls. High-resolution typing revealed significantly higher frequency of HLA-DRB1*10:01 and -DRB1*11:03 among IgAV patients with gastrointestinal manifestations of the disease in comparison to controls (p = 0.0021 and p = 0.0301, respectively), while HLA-DRB1*14:01P occurred significantly more often in the group of patients who developed nephritis during the course of the disease (17.5% vs. 4.5%, p = 0.0006). Our results demonstrated that there is an association of HLA-A*03, HLA-B*37 and HLA-DRB1*12 alleles with susceptibility to IgAV in the examined Croatian pediatric population. Studies which aim to determine the HLA profile may contribute to the elucidation of the genetic background of autoimmune diseases, including IgAV.

Mapping the Human Leukocyte Antigen Diversity among Croatian Regions: Implication in Transplantation

In the present study, HLA allele and haplotype frequencies were studied using the HLA data of 9277 Croatian unrelated individuals, typed using high-resolution methods for the HLA-A, -B, -C, and -DRB1 loci. The total numbers of observed alleles were 47 for HLA-A, 88 for HLA-B, 34 for HLA-C, and 53 for HLA-DRB1. HLA-A^∗02:01 (29.5%), B^∗51:01 (10.5%), C^∗04:01 (15.8%), and DRB1^∗16:01 (10.4%) were the most frequent alleles in the Croatian general population. The three most frequent haplotypes were HLA-A^∗01:01~C^∗07:01~B^∗08:01~DRB1^∗03:01 (4.7%), HLA-A^∗03:01~C^∗07:02~B^∗07:02~DRB1^∗15:01 (1.7%), and HLA-A^∗02:01~C^∗07:01~B^∗18:01~DRB1^∗11:04 (1.5%). Allele and haplotype frequencies were compared between national and regional data, and differences were observed, particularly in the North Croatia region. The data has potential use in refining donor recruitment strategies for national registries of volunteer hematopoietic stem cell donors, solid organ allocation schemes, and the design of future disease and anthropological studies.

HLA-A and -B Type and Haplotype Frequencies in IgG Subclass Deficiency Subgroups

We sought to determine whether HLA-A and -B type and haplotype frequencies differ between subgroups of adults with IgG subclass deficiency (IgGSD). We retrospectively compared type and haplotype frequencies of three subgroups of 269 unrelated adult IgGSD patients (70 subnormal IgG1; 121 subnormal IgG3; 78 subnormal IgG1/IgG3) and controls (1,321 for types; 751 for haplotypes). We selected types and haplotypes because their uncorrected frequencies differed significantly from controls in a previous adult IgGSD/common variable immunodeficiency cohort: A*24; B*14; B*35; B*40; B*49; B*50; B*58; B*62; A*01,B*08; A*02,B*44; A*02,B*60; A*03,B*07; A*03,B*14; A*03,B*44; A*31,B*40; and A*32,B*14. We used χ² analysis (2 × 4 tables) to identify frequency differences across three subgroups and controls. If the null hypothesis was rejected (p < 0.05), we computed 2 × 2 χ² tables to compare six combinations of subgroup and control frequencies [Bonferroni p < 0.0083 (< 0.05/6)]. Mean age was 48 ± 13 years; 82.2% were women. B*35 and B*40 frequencies were higher in subnormal IgG1 than subnormal IgG3 patients (0.1000 vs. 0.0248 and 0.0571 vs. 0.0083, respectively; p ≤ 0.0061). B*62 frequencies were lower in three IgGSD subgroups than controls (p < 0.0001, respectively). A*02, B*44 frequency was higher in subnormal IgG1/IgG3 patients than controls (0.1282 vs. 0.0632, respectively; p = 0.0024). A*02, B*60 frequency was lower in subnormal IgG3 patients than controls (0.0 vs. 0.0233, respectively; p = 0.0051). HLA-B*35 and -B*40 frequencies differ significantly between some IgGSD subgroups. B*62, A*02, B*44, and A*02, B*60 frequencies differ significantly between some IgGSD subgroups and controls.

Detection of novel and confirmation of very rare and rare HLA alleles by next generation sequencing in Croatia

Routine HLA typing in clinical practice encompassing solid organ and hematopoietic stem cells transplantation programs, disease association typing, volunteer marrow donor typing and population studies, provided a large dataset for studying HLA allele polymorphism in the Croatian population which led to the identification of new, very rare and rare HLA alleles. Over the last 4 years we have identified six new HLA alleles (HLA-A*01:200, A*02:836, A*11:01:01:44, B*08:251, B*18:169 and C*05:46:01:02) and a number of very rare (HLA-B*08:78, DRB1*12:39, DRB1*13:23:02 and DQB1*06:09:04) or rare (HLA-A*24:41, B*39:40:01N, B*51:78:01, DRB1*01:31 and DRB1*14:111) alleles using sequence-based typing methods. The reported data enhance the knowledge about HLA polymorphisms in the Croatian population and provide a foundation for further studies in population genetics.

HLA-A, -B, -C, -DRB1, -DQA1, and -DQB1 allele and haplotype frequencies defined by next generation sequencing in a population of East Croatia blood donors

Next-generation sequencing (NGS) is increasingly used in transplantation settings, but also as a method of choice for in-depth analysis of population-specific HLA genetic architecture and its linkage to various diseases. With respect to complex ethnic admixture characteristic for East Croatian population, we aimed to investigate class-I (HLA-A, -B, -C) and class-II (HLA-DRB1, -DQA1, -DQB1) HLA diversity at the highest, 4-field resolution level in 120 healthy, unrelated, blood donor volunteers. Genomic DNA was extracted and HLA genotypes of class I and DQA1 genes were defined in full-length, -DQB1 from intron 1 to 3′ UTR, and -DRB1 from intron 1 to intron 4 (Illumina MiSeq platform, Omixon Twin algorithms, IMGT/HLA release 3.30.0_5). Linkage disequilibrium statistics, Hardy-Weinberg departures, and haplotype frequencies were inferred by exact tests and iterative Expectation-Maximization algorithm using PyPop 0.7.0 and Arlequin v3.5.2.2 software. Our data provide first description of 4-field allele and haplotype frequencies in Croatian population, revealing 192 class-I and class-II alleles and extended haplotypic combinations not apparent from the existing 2-field HLA reports from Croatia. This established reference database complements current knowledge of HLA diversity and should prove useful in future population studies, transplantation settings, and disease-associated HLA screening.

HLA allele and haplotype diversity in the Croatian population: State of the art

The aim of this report was to compare our data with data presented in the European Federation for Immunogenetics (EFI) catalogue (version 1.0) and to evaluate whether or not current (CUR) HLA alleles found in the Croatian population fall into the same categories of common (COM) or well-documented (WD) HLA alleles as those listed in the EFI catalogue. Among 237 HLA-A, -B, -DRB1 alleles observed in the Croatian population so far, 181 alleles were observed ≥3 times. According to our criteria, 36 alleles at HLA-A locus, 71 alleles at HLA-B locus and 51 alleles at HLA-DRB1 locus were characterised as CUR in Croatia (COM or WD in EFI catalogue), while 23 local HLA alleles are not listed at all among COM or WD alleles in EFI catalogue.

Identification of the novel HLA-B*18:37:02 allele in a Croatian individual

The new allele HLA-B*18:37:02 differs from HLA-B*18:37:01 by one nucleotide substitutions in exon 2.

Frequency distribution of HLA alleles and haplotypes in Uyghur women with advanced squamous cell cervical cancer and relation to HPV status and clinical outcome

PURPOSE

This study aims to investigate the association of human leukocyte antigen (HLA) alleles and haplotypes in Uyghur women with advanced squamous cell cervical cancer (SCC).

METHODS

A total of 131 Uyghur patients with advanced SCC (IIb-IVa) and 91 healthy subjects from Xinjiang province were genotyped for HLA-I and II genes using Polymerase Chain Reaction Sequence Based Typing. The different frequencies of HLA alleles and haplotypes between patients and controls were compared and the correlations were analyzed between HLA distribution and HPV status and prognosis.

RESULTS

(1) The frequencies of B*51:01, DRB1*07:01, DQB1*02:01, A*01:01-C*06:02, A*01:01-DRB1*07:01, C*06:02-DQB1*02:01, DRB1*07:01-DQB1*02:01 and C*06:02-DRB1*07:01-DQB1*02:01 in cancer group were higher than control group whereas the frequencies of B*44:02, B*58:01, C*05:01, DRB1*04:01, DRB1*12:01, DRB1*13:01, DQB1*02:02, DQB1*05:02, DRB1*03:01-DQB1*02:02 and DRB1*04:01-DQB1*03:02 in cancer group were lower than control group (P < 0.05). (2) The frequencies of A*01:01-C*06:02, A*01:01-DRB1*07:01, C*06:02-DQB1*02:01, DRB1*07:01-DQB1*02:01 and C*06:02-DRB1*07:01-DQB1*02:01 in HPV positive group were lower than HPV negative group, differences of which were statistically significant (P < 0.05). (3) B*44:02 and B*58:01 were associated with reduced disease-specific survival (DSS) (P = 0.010 and 0.007). (4) Multivariate Cox proportional hazard models revealed that age, International Federation of Gynaecology and Obstetrics (FIGO) stage, tumor differentiation and allele B*58:01 as independent predictors for DSS while FIGO stage and tumor differentiation as independent factors for DFS.

CONCLUSIONS

In the development and progression of advanced SCC among Uyghur population, the HLA alleles and its haplotypes play an important role. B*58:01 allele may act as an independent predictor for DSS.