Association of HLA haplotypes with paroxysmal nocturnal hemoglobinuria.

The pathologies of paroxysmal nocturnal hemoglobinuria (PNH) are primarily caused by somatic mutation in the PIG-A gene in hematopoietic stem cells resulting in glycosyl phosphatidylinositol deficiency and accumulation of phosphatidylinositol (PI) in plasma membranes. The mechanism of pathologic clone domination over normal hematopoietic clones in PNH patients is not yet understood. Forty-four PNH patients, including 9 with aplastic anemia traits (AA/PNH), 31 without full aplasia in bone marrow (de novo PNH, or dn/PNH), and 4 with unclassified PNH, and 200 ethnically matched controls were tested for the HLA A, B, C, DRB1, and DQB1 alleles and haplotype associations. The top block association analysis showed the primary association of PNH with 3 haplotype fragments: the class I fragment A*2501-Cw*1203-B*1801 (risk ratio [RR], 6.64; P=.00012), and 2 class II fragments: DRB1*1501-DQB1*0602 (RR, 7.09; P=.0000015) and DRB1*0401-DQB1*0301 (RR, 6.76, P=.0093). The stratified analysis revealed that the A*2501-Cw*1203-B*1801 haplotype associated preferentially with AA/PNH, and its component HLA molecule showed immunodominant antiapoptotic peptides derived from PI-activated phospholipase D; whereas the DRB1*1501-DQB1*0602 haplotype was associated strongly with dn/PNH and presented immunodominant class II-derived autopeptides. We concluded that certain HLA haplotypes were associated with PNH much more strongly than their allelic components. At least 3 HLA haplotype blocks (A*2501-Cw*1203-B*1801, DRB1*1501-DQB1*0602, and DRB1*0401-DQB1*0301) were primarily associated with PNH. Our results supported the hypothesis of the roles in AA/PNH of antiapoptotic and in dn/PNH of autoimmune mechanisms.

Allele and extended haplotype polymorphism of HLA-A, -C, -B, -DRB1 and -DQB1 loci in Polish population and genetic affinities to other populations.

Human leukocyte antigen (HLA)-A, -C, -B, -DRB1 and -DQB1 alleles were typed in 200 Polish healthy volunteers recruited for stem cell donor registry, using sequence-specific primer (SSP) and direct sequencing-based methods. Enhanced Bayesian approach of expectation maximization algorithm provided by phase platform was used for extended HLA haplotype inferences. The numbers of identified alleles (four-digit resolution) were 23, 23, 44, 27 and 18 alleles in HLA-A, -C, -B, -DRB1 and -DQB1 loci, respectively, of both northern and southern European frequency characteristics. The most frequent extended haplotypes were Cw*0701-B*0801-DRB1*0301-DQB1*0201 and Cw*0702-B*0702-DRB1*1501-DQB1*0602, found in 25 and 23 copies, respectively, in 400 tested chromosomes. The extended haplotype found in the Polish population with higher frequency than in other European population was A*2501-Cw*1203-B*1801-DRB1*1501-DQB1*0602 (six copies) and especially its class I fragment (14 copies). The neighbour-joining and correspondence analyses showed Central and northern European genetic affinities of Polish population. In most cases, the observed European allele and haplotype gradients display smooth topography around Polish population. Poles along with Western Slavs have their specific contribution in the demographic history of Europe. Our results will intensify the use of population data in stem cell donor search and can potentially improve current algorithms, facilitating selection of acceptable donors for patients in need of stem cell transplant.

Haplotype-specific pattern of association of human major histocompatibility complex with non-Hodgkin's lymphoma outcome.

In the previous studies, some human major histocompatibility complex (MHC) genes such as TNF, LTA and human leukocyte antigen (HLA)-DR2 genes and A1-B8-TNF(-308A) haplotype were implied in non-Hodgkin's lymphoma (NHL) outcome. In the current study, we have assigned most probable six-locus haplotypes determined by HLA-A, -Cw, -B and -DRB1 highly polymorphic genes and non-HLA LTA(+252) and TNF(-308) single nucleotide polymorphisms (SNPs) in 152 NHL Caucasian French patients. We have broadly mapped the MHC region by its component blocks and tagging alleles. Ten frequent (with haplotype frequency >1%) six-locus extended haplotypes (EHs) were revealed in NHL patients. The only two adjacent locus fragment of 8.1 EH associated with shortened freedom from progression (FFP) was B*08-LTA(+252G) (P= 0.0084, RR = 2.45). Interestingly, 305-kbp-long, four-locus fragment of 8.1 EH, Cw*07-B*08-LTA(+252G)-TNF(-308A) block was much strongly associated with shortened FFP (P= 0.00045, RR = 3.26). The analysis of further extended haploblocks comprising five or six loci showed weaker association with outcome measures, suggesting linkage disequilibrium to be the cause of DRB1*03 and A*01 allele associations. In contrast, all fragments of 7.1 EH influenced FFP favorably with top association of TNF(-308G) allele. In multivariate analysis, only Cw*07-B*08-LTA(+252G)-TNF(-308A) and TNF(-308G)-DRB1*01 haplotypes remained predictive for shortened FFP (P= 0.024 and 0.027, respectively) and independent of International Prognostic Index (P= 0.00044). This study reveals that the block composition of EHs may cause important functional differences for NHL outcomes. Further study will be required in NHL patients by fine mapping with dense microsatellite or SNP tags to define susceptibility genes in associating regions.