HLA-B gene somatic insertion/deletion mutations in patients with acute myelogenous leukaemia.

Loss of heterozygosity is considered to be the most common type of tumour-specific somatic mutation of the human leucocyte antigens (HLA) genes in patients with haematological malignancies. Nevertheless, subtle DNA sequence changes, namely short insertions/deletions, may also abolish the expression of HLA molecules and interfere with routine HLA typing. Two male patients with acute myelogenous leukaemia (AML) were indicated for the search of a suitable donor for allogeneic haematopoietic stem cell transplantation (aHSCT). The patients and their relatives were initially HLA typed by serological and DNA techniques at a low-resolution level. The HLA high-resolution (HR) type was obtained by means of sequencing-based typing (SBT). In both cases, anomalous frameshifts in the sequence were observed in the HLA-B gene, namely in exon 3 (Case 1, heterozygous deletion of two bases) and exon 4 (Case 2, heterozygous insertion of two bases). In the second case, the insertion variant was associated with a loss of HLA-B8 expression. To reveal whether these sequence patterns may be caused by somatic mutations in the malignant cells, blood sample in remission (Case 1) and buccal swab sample (Case 2) were collected from the patients. In an important manner, the SBT in these germline samples revealed common HLA-B*07:02,*15:01 (Case 1) and HLA-B*08:01,*35:02 (Case 2) types with no evidence for the sequence alteration observed in the initial samples. In conclusion, the insertion/deletion sequence variants of the HLA-B gene in two patients were limited to the initial blood samples with a substantial proportion of AML cells and thus may be attributed to the somatic mutation in the malignant cells. HLA somatic mutations should be taken into account in patients with haematological malignancies to prevent HLA mistyping and inappropriate selection of an aHSCT donor.

Profile of Inflammation-Associated Proteins in Early Post-Transplant Samples of Patients After Allogeneic Hematopoietic Stem Cell Transplantation: a Preliminary Study.

Allogeneic hematopoietic stem cell transplantation (aHSCT) is used as a curative treatment in severe hematological and immunological disorders. Despite clear improvement of the aHSCT outcome, substantial proportion of patients still suffers from severe complications, including graft-versus-host disease (GvHD). The aim of this study was, therefore, to identify inflammation-associated molecules deregulated in the early serum samples of the patients after aHSCT and nominate markers associated with particular aHSCT parameters/complications. Serum concentrations of 92 inflammation-associated proteins were measured in samples obtained from 80 aHSCT patients 14 days after transplantation and from 23 healthy control subjects by a novel sensitive proximity extension assay technology using Proseek Multiplex Inflammation I kit. Serum profiles of inflammatory proteins in patients after aHSCT were substantially different from those observed in control subjects and related to underlying disease status before transplantation. Particularly, the difference between aHSCT patients and controls reached significance level for 57 analytes (40 upregulated, 17 downregulated in aHSCT patients). The concentration of several markers was associated with the level of donor/recipient HLA match (TGF-α: p corr = 0.025, HGF: p corr = 0.036) and with complete donor chimerism at day +30 after allografting (DNER: p corr = 0.042). None of the markers was significantly associated with acute and chronic GvHD after correction. More than half of investigated proteins significantly differed between the samples from aHSCT patients and healthy control subjects as a consequence of the "cytokine storm" after aHSCT. Comparisons of patient's subgroups based on specific biological/clinical parameters revealed much less evident differences; nevertheless, we nominated several markers associated with the level of donor/recipient HLA match and post-transplant chimerism.

ATM gene single nucleotide polymorphisms predict regimen-related gastrointestinal toxicity in patients allografted after reduced conditioning.

Polymorphisms of genes involved in innate and adaptive immunity have become an object of major interest in regard to hematopoietic stem cell transplantation (HSCT) complications. Regimen-related gastrointestinal toxicity (RR-GIT) is the dominant complication during the pre-engraftment period and has been linked to increased risk of graft-versus-host disease (GVHD) development. According to our hypothesis, functional variants of genes participating in DNA damage response (DDR) may have an impact on the extent of tissue damage caused by the conditioning regimen. In our single-center study, we analyzed 62 patients who underwent HSCT from HLA-identical donors after reduced conditioning. The patients were genotyped for 5 single nucleotide polymorphisms (SNPs, rs4585 T/G, rs189037 A/G, rs227092 T/G, rs228590 C/T, and rs664677 T/C) of the ATM gene-the essential member of the DDR pathways, using allele-specific matrix-assisted laser desorption/ionization, time-of-flight (MALDI-TOF) mass spectrometry assay. Because of almost absolute linkage disequilibrium observed among all 5 SNPs, association of 2 major ATM haplotypes (ATM1/ATM2) with RR-GIT and acute GVHD (aGVHD) was analyzed. Importantly, the univariate and multivariate analysis showed that patients homozygous for ATM2 haplotype (rs4585*T, rs189037*A, rs227092*T, rs228590*C, and rs664677*T) are more likely to suffer from high-grade RR-GIT than ATM1 homozygous patients. The association with aGVHD was not significant. To our knowledge, this is the first report showing the ATM gene variability in relation to RR-GIT in the allogeneic HSCT setting.

Possible impact of MADCAM1 gene single nucleotide polymorphisms to the outcome of allogeneic hematopoietic stem cell transplantation.

Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) contributes to the recruitment of donor T cells into the mucosal tissues of the recipient after allogeneic hematopoietic stem cell transplantation (aHSCT). The aim of our study was to determine whether selected single nucleotide polymorphisms (SNPs) of the MADCAM1 gene are associated with development of serious complications after aHSCT. Three MADCAM1 gene single nucleotide polymorphisms (rs758502 C/T, rs2302217 A/G, rs3745925 G/T) were genotyped by polymerase chain reaction with sequence-specific primers in 87 Czech, HLA-identical donor-recipient aHSCT pairs. MADCAM1 rs2302217 AA homozygous recipients developed chronic GVHD more frequently than patients with other genotypes (65% vs. 34%; p = 0.025). Furthermore, multivariate analysis revealed the MADCAM1 rs2302217 AA genotype in recipient being also an independent factor associated with development of acute GVHD (p = 0.036) and decreased overall survival (p = 0.001). These data suggest that MADCAM1 gene polymorphisms may be associated with the risk of chronic GVHD and may, also, affect mortality related to aHSCT.