Description of a new DRB1*11 allele (DRB1*1132)

We describe a new DRB1*11 allele which is similar to DRB1*11011 except at codon 74, where a GCG is changed for a GTG leading to an alanine/valine substitution. This new allele was carried by a Caucasian patient suffering from rheumatoid arthritis and by her healthy daughter. The motif at codon 74 of the new DRB1*11 is not found in any other known DRB alleles, nor among the published DQA1, DQB1, DPA1 or DPB1 alleles, and therefore suggests a mechanism of point mutation.

New susceptibility locus for rheumatoid arthritis suggested by a genome-wide linkage study

Rheumatoid arthritis (RA), the most common autoimmune disease, is associated in families with other autoimmune diseases, including insulin-dependent diabetes mellitus (IDDM). Its genetic component has been suggested by familial aggregation (lambdas = 5), twin studies, and segregation analysis. HLA, which is the only susceptibility locus known, has been estimated to account for one-third of this component. The aim of this paper was to identify new RA loci. A genome scan was performed with 114 European Caucasian RA sib pairs from 97 nuclear families. Linkage was significant only for HLA (P < 2.5.10(-5)) and nominal for 19 markers in 14 other regions (P < 0.05). Four of the loci implicated in IDDM potentially overlap with these regions: the putative IDDM6, IDDM9, IDDM13, and DXS998 loci. The first two of these candidate regions, defined in the RA genome scan by the markers D18S68-D18S61-D18S469 (18q22-23) and D3S1267 (3q13), respectively, were studied in 194 additional RA sib pairs from 164 nuclear families. Support for linkage to chromosome 3 only was extended significantly (P = 0.002). The analysis of all 261 families provided a linkage evidence of P = 0. 001 and suggested an interaction between this putative RA locus and HLA. This locus could account for 16% of the genetic component of RA. Candidate genes include those coding for CD80 and CD86, molecules involved in antigen-specific T cell recognition. In conclusion, this first genome scan in RA Caucasian families revealed 14 candidate regions, one of which was supported further by the study of a second set of families.

Mitochondrial DNA sequence variation in human leukemic cells

The Long PCR followed by the RFLP technique has been used to search for abnormally structured mitochondrial DNA (mtDNA) and specific sequence differences implicated in the pathogenesis of acute lymphoblastic leukaemia (ALL). We have studied 54 specific sites whose combinations define groups of mtDNA types, in 30 leukemic patients of French Caucasian origin. Results were compared with those in 100 French healthy individuals. Nucleotide substitutions have been defined in 11 patients. This polymorphism is expressed by single base substitution at 6 sites which corresponds to 5 morphs, 2 of which were not found in the reference group. Combining the 11 observed morphs, we have identified 7 different mtDNA types, defined in 30 patients with ALL. Two of the morphs (MspI-2 and AvaII-3) and 3 of the types (17-2, 55-2, NewFr150) were not found in the group of healthy individuals. We have observed significant statistical changes in type 28-2 in ALL patients compared with the controls.

Mitochondrial DNA sequence variation in human leukemic cells

The Long PCR followed by the RFLP technique has been used to search for abnormally structured mitochondrial DNA (mtDNA) and specific sequence differences implicated in the pathogenesis of acute lymphoblastic leukaemia (ALL). We have studied 54 specific sites whose combinations define groups of mtDNA types, in 30 leukemic patients of French Caucasian origin. Results were compared with those in 100 French healthy individuals. Nucleotide substitutions have been defined in 11 patients. This polymorphism is expressed by single base substitution at 6 sites which corresponds to 5 morphs, 2 of which were not found in the reference group. Combining the 11 observed morphs, we have identified 7 different mtDNA types, defined in 30 patients with ALL. Two of the morphs (MspI-2 and AvaII-3) and 3 of the types (17-2, 55-2, NewFr150) were not found in the group of healthy individuals. We have observed significant statistical changes in type 28-2 in ALL patients compared with the controls.

Association of rheumatoid arthritis with an amino acid allelic variation of the T cell receptor

OBJECTIVE

To investigate allelic variations of T cell receptor residues for a contribution to rheumatoid arthritis (RA) susceptibility.

METHODS

We conducted an RA case-control study involving 1,579 northwest Europeans: 766 patients with erosive and rheumatoid factor-positive disease and 813 control subjects. Productive changes of segments TCRAV6S1, TCRAV7S1, TCRAV8S1, TCRAV10S2, and TCRBV6S1, TCRBV6S7 were investigated by single-strand conformation polymorphisms. The TCRAV8S1 association was confirmed by restriction fragment length polymorphism.

RESULTS

In the systematic study (77 patients and 119 controls), an increase in 1 TCRAV8S1 genotype was found in the RA patients (P = 0.0004). This finding was replicated in 2 further populations, one from France (212 patients and 254 controls) and the other from Britain (477 patients and 440 controls), with a similar odds ratio (OR), which allowed pooling of the data and confirmation of the association (OR 1.3 [95% confidence interval 1.1-1.7], P = 0.008).

CONCLUSION

These findings show evidence that TCRA is an RA susceptibility locus.

Association of HLA class II genes with susceptibility to Crohn's disease

BACKGROUND

Published studies on the association between HLA class II genes and inflammatory bowel disease are contradictory perhaps because of the limited size and ethnic heterogeneity of the populations studied.

AIM

To compare the frequencies of HLA class II genes in a large number of French patients with Crohn's disease and in an ethnically matched control group.

METHODS

344 patients (196 F, 148 M, mean age 23.6 years) with Crohn's disease were molecularly genotyped for the HLA-DQB1 and DRB1 alleles. The results were compared with those for an ethnically matched control population of 488 white adults.

RESULTS

There were two significant variations of alleles at the DQB1 locus: an increase in DQB1*0501 allele frequency (chi 2 = 10.6, corrected p value (pc) = 0.01, odds ratio (OR) = 1.61) and a decrease in DQB1*0602/0603 allele frequencies (chi 2 = 8.43, pc = 0.037, OR = 0.66). DRB1 analysis showed associations with three allelic variations: an increase in the frequencies of DRB1*01 (chi 2 = 12.86, pc = 0.003, OR = 1.75) and DRB1*07 alleles (chi 2 = 11.18, pc = 0.008, OR = 1.58) and a very significant decrease in that of the DRB1*03 allele (chi 2 = 19.7, pc = 9.10(-5), OR = 0.46).

CONCLUSION

The alleles DRB1*01 and DRB1*07 are associated with susceptibility to Crohn's disease. The strong negative association between the DRB1*03 allele and Crohn's disease suggests that the HLA-DRB1*03 allele mediates 'resistance' to Crohn's disease.

Decreased frequency of HLA-DRB1 13 alleles in Frenchwomen with HPV-positive carcinoma of the cervix

Specific types of human papillomaviruses (HPV) are associated with most cases of pre-invasive and invasive neoplasia of the uterine cervix. HLA phenotype influences susceptibility and resistance to viral infections and may therefore influence the course of HPV-associated tumors. Some data suggest that specific HLA class-II alleles may be associated with protection from or susceptibility to papillomavirus-associated lesions, but these results are still controversial. Using molecular probes, we looked for associations between specific DQA1, DQB1, DRB1 HLA class-II alleles, HPV types and cervical cancer. The analysis was performed on a population of 126 patients with invasive cervical cancer. For HLA typing, 165 healthy individuals were taken as controls. The DRB1 1301/02 allele frequency significantly decreased in patients (11%) as compared to controls (29%). This difference in frequency was dependent on the HPV-positive status of tumors and was no longer significant in the group of HPV-negative lesions. The same trends were observed with the DRB1 1301/02-DQA1 0103-DQB1 0603 haplotype frequency. An increase in the frequency of the DRB1 1401/07 and DRB1 03 alleles was observed in patients under 40. Contrary to what has been reported in the literature, no increase in the DRB1 15 allele frequency was observed in our series and only a slight increase in the DQB1 03 frequency was found in patients (70%) compared to controls (58%). In our study, no positive correlations between cervical cancer in Frenchwomen and specific HLA DR-DQ haplotypes has been found. In contrast, a negative correlation between DRB1 1301/ 02 alleles and HPV-positive tumors has been observed. This may suggest a protective effect of DR13 against HPV-associated lesions of the cervix.

HLA-DRB1, DQA1, DQB1 DNA polymorphism in the Bulgarian population

We describe for the first time the use of PCR based techniques to analyze the MHC class II polymorphism of the Bulgarian population. The present study provides the HLA-DRB, DQB1 allele frequencies in 116 Bulgarian individuals and DQA1 alleles frequencies in 100 subjects. DNA from these individuals was typed for DRB and DQB1 typed by the PCR-Allele Specific Amplification (PCR-ASA) method and DQA1 by PCR followed by hybridization using Sequence Specific Oligonucleotides (PCR-SSO). Allele and haplotype frequencies and linkage disequilibria are computed by the standard methods used for the XIth International Histocompatibility Workshop. The highest frequencies are 0.159, 0.109 and 0.085 for DRB1*1101, DRB1*1601 and DRB1*1301 respectively. Among the eight DQA1 alleles detected, DQA1*0501 (0.344) is found to be much more frequent than the two most frequent alleles DQA1*0102 (0.225) and DQA1*0101 (0.151). Twelve DQB1 alleles are found and three of them, DQB1*0301 (0.280), DQB1*0502 (0.153) and DQB1*0201 (0.133) showed the highest frequencies. The haplotype DRB1*1101-DQA1*0501-DQB1*0301 (0.079) predominate clearly, followed by DRB1*1601-DQA1*0102-DDQB1*0502 (0.055) and DRB1*0101-DQA1*0101-DQB1*0501. These results indicate that the Bulgarian population is characterized by features representative of the European anthropological type with a substantial contribution from the Southern Belt of Europe.

Determination of DQB1 alleles using PCR amplification and allele-specific primers

Molecular genotyping of HLA class II genes is commonly carried out using polymerase chain reaction (PCR) in combination with sequence-specific oligotyping (PCR-SSO) or a combination of the PCR and restriction fragment length polymorphism methods (PCR-RFLP). However, the identification of the DQB1 type by PCR-SSO and PCR-RFLP is very time-consuming which is disadvantageous for the typing of cadaveric organ donors. We have developed a DQB1 typing method using PCR in combination with allele-specific amplification (PCR-ASA), which allows the identification of the 17 most frequent alleles in one step using seven amplification mixtures. PCR allele-specific amplification HLA-DQB1 typing is easy to perform, and the results are easy to interpret in routine clinical practice. The PCR-ASA method is therefore better suited to DQB1 typing for organ transplantation than other methods.

Trans-encoded DQ alpha beta heterodimers confer susceptibility to myasthenia gravis disease

Myasthenia gravis (MG) is an autoimmune disease associated with thymic abnormalities (hyperplasia and thymoma). With classical typing method, no clear association was observed between HLA class II and MG disease except in a subgroup of patients with hyperplasia. The aim of our work was to investigate a possible correlation between HLA class II alleles and MG disease using molecular typing which was proved to be much more informative in many diseases. Using polymerase chain reaction and 75 sequence-specific oligonucleotide probes, frequencies of HLA-DRB1, B3, B4, DQA1, DQB1 and DPB1 alleles were identified in 47 Caucasian MG patients and 105 healthy controls. None of the HLA class II alleles identified, was significantly increased in the group of patients compared to controls. However, further analysis of DQA1-DQB1 genotype demonstrated that susceptibility to the disease is associated with two trans DQ alpha beta heterodimers encoded by DQA1*01-DQB1*0201 or DQA1*01-DQB1*0301 combinations (72% in patients vs 29% in controls, RR = 6.2, Pc < 0.001). DQA1*01 group of alleles (DQA1*0101, 0102 or 0103 allele) encode DQ alpha chains sharing long polymorphic sequence including non-charged glycine and positively charged arginine residues at positions 55 and 64, respectively. DQB1*0301 and DQB1*0201 encode a DQ beta chain bearing a negatively charged glutamic acid at position 45 and 46, respectively. A combination of such DQ alpha and DQ beta chains may form susceptibility peptide-binding groove. In MG patients with thymic hyperplasia an additional association with DQA1*0501 in linkage disequilibrium with DQB1*0201 and DQB1*0301 alleles was observed (RR = 17.2, Pc < 0.001). Our data indicate that MG, like other autoimmune diseases, is associated with particular HLA-DQ alpha beta heterodimers, independently of clinical parameters. A role for DQA1*0501 allele in the manifestation of thymic hyperplasia disorders is suggested.

HLA class II polymorphism and IDDM susceptibility in the Greek population

The frequencies of HLA-DQA1, DQB1 and DRB1 alleles were compared between 50 Insulin-Dependent Diabetes Melitus (IDDM) patients and 49 healthy controls in the Greek population. Statistically significant difference in the frequencies of HLA-DQA1*0501-DQB1*0201 (P = 10(-4)), DQA1*0301-DQB1*0201 (P = 0.01) and DQA1*0301-DQB1*0302 (P = 0.001) were observed. The DRB1*0405-DQA1*0301-DQB1*0201 was the only DR, DQ combination significantly associated with the disease. The unexpected increase of DRB1*0405 observed in the Greek IDDM may suggest as reported in Chinese and Japanese IDDM a contribution of DR beta and DQ alpha in susceptibility. Moreover, in contrast to the Asians, in the Greek, the DR beta, DQ alpha are found with the usual DQ beta 57-ve.