Six new DPB1 alleles identified in a study of 1,302 unrelated bone marrow donor-recipient pairs

Six new DPB1 alleles were identified by PCR-SSOP methodologies in the course of a retrospective study of the role of HLA matching in the outcome of unrelated donor bone marrow transplantation. Sequencing confirmed that five of these alleles (DPB1*5901, *6801, *7101, *7201, and *7301) represent novel combinations of previously described sequence motifs in the variable regions of DPB1; the sixth (DPB1*7001) appears to result from a novel point mutation. These data support previous observations which suggest that multiple mechanisms, including segmental exchange and mutation, appear to be responsible for generating sequence diversity at the DPB1 locus. The extremely low discrepancy rate of 0.1% between the two laboratories which typed the samples, and the ability to predict the new sequences from probe hybridization patterns, indicate that SSOP is an accurate and efficient method for studying polymorphism at DPB1.     

Three new DPB1 alleles identified in a Bantu-speaking population from central Cameroon

HLA-DPB1 genotyping of 241 individuals from an African Bantu-speaking population in central Cameroon using sequence-specific oligonucleotide probes identified five individuals with novel probe hybridization patterns. DNA sequence analysis of the second exon of the DPB1 alleles from these five individuals identified three new alleles, *6001, *6101N, and *6201. DPB1*6001, found in two individuals, contains a single nucleotide change that results in a polar amino acid, asparagine, at residue 65; this position in the β1 domain is occupied by a nonpolar amino acid in all other reported DPB1 alleles. DPB1*6101N, found in one individual, contains a single base mutation that results in a premature termination codon at position 67. DPB1*6201, found in two individuals, is characterized by the apparent motif shuffling that has been hypothesized to be responsible for the majority of DPB1 sequence polymorphism. These new sequences shed additional light on the potential mechanisms by which allelic diversity is generated at the HLA-DPB1 locus.     

Three new DP alleles identified in sub-Saharan Africa: DPB1*74O1, DPAl*02013, and DPAl*0302

Abstract: HLA-DP genotyping of over 400 individuals from sub-Saharan Africa identified three new DP alleles: DPB1*7401, DPAl*02013, and DPAl*0302. DNA sequencing confirmed that DPB1*7401, found in one individual, is a novel combination of previously described sequence motifs in the six variable regions of DPB1. DPA1*02013, found in one individual, is identical to DPAl*02012 except for two silent substitutions, a T to C transition in codon 37, and an A to G transition in codon 38. DPAl*0302, identified in seven individuals, is identical to DPAl*0301 except for a C to T transition at the second position of codon 66. The identification of these novel alleles brings the total number of reported DPB1 alleles to 77 and DPA1 alleles to 11.     

Three new DP alleles identified in a study of 800 unrelated bone marrow donor-recipient pairs

HLA-DP genotyping of 800 unrelated donor-recipient pairs in phase 5 of a retrospective analysis of unrelated bone marrow transplantation, sponsored by the National Marrow Donor Program (NMDP), has identified two new DPB1 alleles (DPB1*8701 and DBP1*8801) and one new DPA1 (DPA1*0108) allele. Sequencing confirmed that all three of these new alleles represent novel combinations of previously described sequence motifs, reinforcing the notion that "gene conversion-like" events play an important role in generating HLA allelic diversity. The identification of these new alleles brings the total number of DPA1 alleles to 20 and the total number of DPB1 alleles to 94.     

Two new HLA DPB1 alleles identified by sequence-based typing: DPB1*8201 and DPB1*8301

Two new HLA DPB1 alleles were identified by sequence-based typing and are reported. Both alleles differ from DPB1*0402 by a single nucleotide: DPB1*8201 has a difference at position 359 (codon 91) leading to an amino acid change from arg to his, making this position a new polymorphic site; DPB1*8301 has a difference at position 280 (codon 65) changing the amino acid from ile to phe.     

Four new DP alleles identified in a study of 500 unrelated bone marrow donor-recipient pairs

HLA-DP genotyping of 500 donor recipient pairs in a retrospective analysis sponsored by the National Marrow Donor Program (NMDP) identified four new DP alleles, two DPB1 and two DPA1. DNA sequencing confirmed that DPB1*8001 and *8101, each found in a single individual, are novel combinations of previously described sequence motifs in the six variable regions of DPB1. DPA1*02014, found in two individuals, is identical to DPA1*02011 except for a novel silent substitution, a G to A transition at the third position of codon 14. DPA1*01032, found in one individual, is identical to DPB1*01031 except for a silent G to A transition at the third position of codon 20. The identification of these novel alleles brings the total number of reported DPB1 alleles to 85 and DPA1 alleles to 15.     

DQCAR 113 and DQCAR 115 in combination with HLA-DRB1 alleles are significant markers of susceptibility to rheumatoid arthritis in the Korean population

We have investigated HLA region microsatellite polymorphisms in rheumatoid arthritis (RA) which are known to be associated with HLA class II alleles in the Korean population. Ninety patients with RA and 106 controls were employed for this study, in which TAP1CA, DQCAR, D6S273, HLA-DRB1, -DQA1 and -DQB1 allele typing were performed. DQCAR 113 (RR = 3.2, P<0.0002), DQCAR 115 (RR = 3.6, P<0.0001) and heterozygous DQCAR 113/115 (RR = 11.2, P<0.0001) frequencies were significantly increased in the RA group compared with the control group. The HLA-DRB1 genotypes of patients who had DQCAR 113/115 alleles were defined as DRB1*04 and/or DRB1*09. There was no significant difference between RA and controls in D6S273 and TAP1CA allele frequencies. We demonstrated that HLA-DRB1*0405 (RR = 6.6, P<10(-6)), DQA1*03 (RR = 5.2, P<10(-6)), DQB1*04 (RR = 3.5, P<0.002) alleles were useful markers of susceptibility to RA in Koreans. The frequency of HLA-DRB1*0405 was higher in DQCAR 113 allele-positive RA (68.1%) than in DQCAR 113 allele-negative (16.3%) and total RA (43.3%) groups, and the susceptibility risk of DQCAR 113 allele to RA was more increased in the DRB1*0405-positive group (RR = 5.5, P<0.04). On the other hand, DQCAR 115 allele was more significantly associated with susceptibility to RA in HLA-DRB1*0405-negative patients (RR = 5.1, P<0.0005), and the association between RA and HLA-DRB1*0405 was also significantly associated with DQCAR 115 allele-negative patients (RR = 13.2, P<0.00001) as compared with DQCAR 115 allele-negative control groups. HLA-DRB1*0405-DQA1*03-DQCAR113-DQB1*03 haplotype showed high relative risk value (RR= 17.7, P<0.0002). In conclusion, the DQCAR allele in combination with HLA class II, especially DR, is probably a useful risk marker for RA susceptibility in the Korean population.     

Autoantibodies to DNA topoisomerase II in juvenile rheumatoid arthritis.

Sera from 58 children with juvenile rheumatoid arthritis were examined for the presence of antibodies to DNA topoisomerase II. Eight sera were reactive in immunoblotting with purified human topoisomerase II and a protein encoded by a cloned cDNA expressed in Escherichia coli which represents the carboxy-terminal domain of the human enzyme. In addition, the sera detect topoisomerase II in mitotic chromosomes and chromosome scaffolds. Five of the sera bind to the native enzyme in solution and deplete such solutions of the active enzyme. All eight sera also contain antibodies to nuclear antigens other than topoisomerase II.     

Association of the HLA-G 14-bp insertion/deletion polymorphism with juvenile idiopathic arthritis and rheumatoid arthritis

We tested the possible association of the 14-bp polymorphism of the HLA-G gene in the course of two inflammatory diseases, rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA). Patients and controls were genotyped for the 14-bp polymorphism by polymerase chain reaction with specific primers for the exon 8 of the human leukocyte antigen (HLA)-G gene and the amplified fragment was visualized in a 6% polyacrylamide gel. A total of 106 JIA patients, 265 RA patients, 356 healthy adults and 85 healthy children were genotyped for the 14-bp polymorphism. Female JIA patients presented a higher frequency of the -14 bp allele when compared with female healthy children (0.743 and 0.500, corrected P=0.003), which reflected in the JIA group as a whole. This increased frequency of the -14-bp allele was observed in all JIA subtypes. In RA patients, no differences in allelic and genotypic frequencies were observed between patients and controls. No correlations were observed among genotype and disease severity or clinical manifestations. Our data suggest that the HLA-G -14 bp allele is probably a risk factor for JIA, mainly in females. Considering the differences observed in relation to gender, we suggest that hormonal differences can interfere with the development of JIA. Considering the RA patients, our data agree with results from the literature and highlight the differences in the etiology of RA and JIA.     

The nucleotide sequence of two new DP alleles, DPA1*02015 and DPB1*8401, identified in a Chinese subject

The HLA-DP genes (HLA-DPA1 and -DPB1) are encoded by the major histocompatibility complex (MHC) on human chromosome 6. They are involved in the presentation of antigen to CD4+ T cells as part of the class II antigen-presentation pathway. During a small study of Oriental subjects (11 Chinese and 26 Japanese subjects), one Chinese subject was identified as having numerous heterozygous sites within the second exon of both DPA1 and DPB1. These were further analysed using novel codon-specific primers. Sequencing analysis using these primers determined the subject to have DPA1*0103/*02015 and DPB1*0501/*8401; these new alleles have been submitted to GenBank and assigned the accession numbers AF098794 and AF077015, respectively.     

Association of NRAMP1 promoter gene polymorphism with the susceptibility and radiological severity of rheumatoid arthritis

The natural resistant-associated macrophage protein 1 (NRAMP1) has been proposed as a candidate gene for the susceptibility to autoimmune diseases. In this study, the possible role of the functional polymorphism located at the promoter region of NRAMP1 gene in the susceptibility and clinical outcome of rheumatoid arthritis (RA) was investigated. A total of 141 Spanish RA patients and 194 controls previously typed for HLA-DRB1* were genotyped for the NRAMP1 polymorphism. No significant differences in the distribution of frequencies among RA patients and controls were observed. Nevertheless, when patients and controls were stratified according to their HLA shared epitope (SE) status, an increase of 2/2 genotype among SE-negative (SE-) patients with respect to SE- controls was observed (23% vs 7%, OR = 3.74, 95% CI 1.31-10.72). In addition, the possible role of this polymorphism in the clinical course of RA was investigated in a subgroup of 82 patients who were prospectively followed during a mean of 9 years. After follow-up, an increase of patients with the homozygous 2/2 genotype was detected among those with severe small joint radiological involvement: 73% of patients 2/2 had a severe form in contrast to 37% of patients with the genotype 2/3 and 30% of patients bearing 3/3 OR = 5.45, 95% CI 1.14-34.24). In conclusion, NRAMP1 gene promoter polymorphism could influence the radiological severity of rheumatoid arthritis and disease susceptibility, particularly in individuals lacking HLA-linked risk factors.     

中国人类风湿关节炎与PAD14功能基因多态性及部分HLA-DRB1等位基因相关性研究

目的 分析类风湿关节炎(rheumatoid arthritis,RA)中4型肽精氨酸转亚胺基酶(peptidylarginine deiminase IV,PAD14)功能基因多态性,探讨PAD14基因多态性与RA易感性的关系,以及编码与RA易感性相关HLA共同表位(shared epitope,SE)的HLA-DRB1等位基因与PAD14基因多态性的相关性.方法 采用逆转录合成cDNA、DNA测序和T载体克隆方法 分析67例RA患者、81名正常人PAD14基因外显子4个单核苷酸多态性(single nucleotide polymorphisms,SNPs),包括PADH_89*A/G,PADl4 90*C/T,PAD1492*C/G,PAD14 104*C/T;采用PCR-序列特异性引物方法 分析HLA-DRB1.*-01、*04、* 10基因型.结果 RA患者PAD14 89、90、104位基因多态性分布与正常对照组比差异有统计学意义,携带PAD14少见等位基因者对RA的危险性较携带常见等位基因者显著增加;分析编码SE等位基因与PAD14 SNPs的相关性发现,SE+/PAD14_89G-携带者较SE-/PAD14_89G-携带者发生RA的危险性高4.7倍(OR=4.7,95%CI:1.6～13.4,P=0.003),携带SE+/PAD14 89G+者高5.6倍(OR=5.6,95%CI:2.0～15.7,P=0.003).在PAD14 90、92、104位均出现相似的情况.结论 PAD14功能基因多态性与中国人RA的易感性相关,编码SE的HLA-DRB1等位基因仍然是RA的重要遗传标记,而且HLA-DRB1等位基因与PAD14的少见等位基因间可能存在一定的协同作用.     

Leflunomide in the treatment of rheumatoid arthritis

Rheumatoid arthritis is a chronic and highly morbid disease affecting approximately 1% of the world’s population. With the advent of disease-modifying antirheumatic drugs, patients are increasingly able to maintain control of their arthritis and prevent joint destruction. However, not all patients respond adequately to any single disease-modifying antirheumatic drug, and many newer parenteral therapies are cost prohibitive. Leflunomide, an inhibitor of pyrimidine biosynthesis, is the first oral disease-modifying antirheumatic drug to have been approved for rheumatoid arthritis in the USA in the last 15 years, and is now widely used in over 70 countries around the world. Leflunomide is efficacious when used as monotherapy or in combination with methotrexate to treat patients with rheumatoid arthritis, and is generally well tolerated. As clinical use increases, new ways to use leflunomide in order to minimize toxicity and maximize efficacy are being explored.