HLA class II genotypes in Mexican Mestizo patients with myasthenia gravis

Human Leucocyte Antigen B50 Is Associated with Conversion to Generalized Myasthenia Gravis in Patients with Pure Ocular Onset

OBJECTIVES

The aim of this study was to investigate the associations between major histocompatibility complex (MHC) class I and II alleles and disease characteristics in Turkish patients with myasthenia gravis (MG).

SUBJECTS AND METHODS

The MHC class I and II alleles of 108 unrelated MG patients were genotyped. The human leucocyte antigen (HLA) distribution of all MG patients and subgroups of MG patients (grouped according to disease characteristics) was compared to that of 250 healthy controls.

RESULTS

Overall distributions of HLA-B*61 and C*05 were more frequent in MG patients (7.4 vs. 2.0% and 14.8 vs. 6.8%, respectively) than in non-MG patients. Subgroup analyses revealed that HLA-DRB1*14 and DQB1*02 alleles were more frequent in early-onset MG [n = 10 (20.8%) vs. n = 25 (10.0%) and n = 21 (43.8%) vs. n = 59 (23.6%)]. In patients seropositive for anti-AchR antibodies, the frequencies of HLA-B*50 and C*05 were higher. HLA-C*05, DRB1*01, and DRB1*11 were higher in patients with ocular MG. In addition, HLA-A*01, A*31, B*08, and DRB1*14 were higher among patients with thymic hyperplasia, whereas DQB1*03 was lower. However, all of these differences lost significance after correction of the p value for multiple comparisons. No allele association was found among patients with thymoma. Strikingly, patients with generalized MG who had pure ocular symptoms at disease onset had significantly increased HLA-B*50 compared to the controls (corrected p < 0.001, OR = 9.92; 95% CI 3.05-32.22).

CONCLUSION

The HLA-B*50 allele was associated with conversion to generalized disease in patients with pure ocular symptoms at disease onset. This finding could extend our understanding of the complex interactions between the pathogenesis of MG and genetic heritage.

Association of HLA class II (DRB1, DQA1, DQB1) alleles and haplotypes with myasthenia gravis and its subgroups in the Iranian population

Heterogenic pattern of HLA associations with myasthenia gravis (MG) among different ethnicities and also among different MG subgroups has been the subject of debate in large series of many studies. One hundred and sixty Iranian MG patients were investigated for HLA class II (DRB1, DQA1, DQB1) associations compared to two hundred healthy controls from the same ethnic population. DRB1*11 DQA1*0501 DQB1*0301 haplotype was found to be protective for total (ocular plus generalized) MG (Pc=0.005, OR=0.49) and generalized MG (Pc=0.008, OR=0.49). DRB1*04 DQA1*0301 DQB1*0302 haplotype (Pc=0.03, OR=2.25) was predisposing for anti-acetylcholine receptor (AChR) antibody-positive MG, while DRB1*16 DQA1*0102 DQB1*05 (Pc=0.013, OR=4.28) was predisposing for anti-muscle specific tyrosine kinase (MuSK) antibody-positive MG. There was also a trend of positive association for DRB1*14 DQA1*0104 DQB1*05 haplotype with MuSK-positive MG (Pc=0.054, OR=3.97). Among other MG subgroups and with less significance, DRB1*0101 DQA1*0101 DQB1*05 haplotype (P=0.016, OR=3.68) had positive association with pure ocular MG, and DRB1*03 DQA1*0501 DQB1*0201 haplotype (P=0.024) had negative association with thymomatous MG. This study highlights the importance of appropriate MG subgrouping according to clinical and paraclinical characteristics in HLA studies among MG patients.

No association of the HLA-DQ alleles with myasthenia gravis in Cuban patients

Myasthenia gravis (MG) is a neuromuscular disorder characterized by fatigability and weakness of striated muscles. Its association with HLA molecules is well known and varies depending on age, sex and the ethnicity of the patients. A case-control study was performed in 61 Cuban patients and 81 controls using polymerase chain reaction and sequence-specific primers of the HLA-DQA1/B1 alleles. The distribution of the HLA-DQ alleles individually and in a simple haplotype between patients and controls shows no statistically significance differences. This result could be due to the heterogeneity and ethnic admixture existing in Cuban population. These findings indicate that the association between a disease and a particular genetic region cannot be explained merely by similarities in the genetic background but involve environmental and immunological factors.

Association between HLA-DRB1 and myasthenia gravis in a northern Han Chinese population

The cause of myasthenia gravis (MG) is unknown, but it is widely believed to be an autoimmune disease occurring in genetically susceptible individuals. The human leukocyte antigen (HLA) region is considered to be the most important genetic region for MG susceptibility genes. To investigate the association between HLA-DRB1 and myasthenia gravis (MG) in a northern Han Chinese population, a polymerase chain reaction with sequence-specific oligonucleotide probe hybridization method was used to determine the HLA-DRB1 genotypes of 91 patients with MG and 171 healthy individuals. We found that the HLA-DRB1(*)09 allele was significantly more prevalent among patients with MG than among healthy controls, especially those who experienced early onset of the disease (≤40 years), those who were seronegative for acetylcholine receptor antibody, and those with ocular MG. The prevalence of the HLA-DRB1(*)08 allele was significantly lower among patients with MG than among controls. These results indicate that HLA-DRB1(*)09 might be positively associated and DRB1(*)08 negatively associated with MG in the northern Han Chinese population.

HLA-DR alleles determine responsiveness to Borrelia burgdorferi antigens in a mouse model of self-perpetuating arthritis

OBJECTIVE

Arthritis is a prominent manifestation of Lyme disease, which is caused by infection with Borrelia burgdorferi (Bb). Chronic Lyme arthritis persisting even after antibiotic treatment is linked to HLA-DRB1*0401 (DR4) and related alleles. In contrast, patients whose Lyme arthritis resolves within 3 months postinfection show an increased frequency of HLA-DRB1*1101 (DR11). The aim of this study was to analyze the underlying mechanism by which HLA-DR alleles confer genetic susceptibility or resistance to antibiotic-refractory Lyme arthritis.

METHODS

We generated DR11-transgenic (DR11-Tg) mice on a murine MHCII-/- background and compared their immune response to Bb antigens with the response of DR4-Tg mice after immunization with Bb outer surface protein A (OspA) or infection with live Bb.

RESULTS

T cells from OspA-immunized and Bb-infected DR11-Tg mice had defective production of interferon-gamma as compared with those from DR4-Tg mice. In contrast, DR11-Tg mice developed higher titers of anti-OspA and anti-Bb antibodies, respectively, than did DR4-Tg mice. Consistent with this observation, we found that the Bb-infected DR11-Tg mice had a decreased spirochetal burden as compared with the DR4-Tg mice, as measured by quantitative polymerase chain reaction.

CONCLUSION

This study provides direct evidence that in the presence of HLA-DR11, the immune response against Bb antigens is directed toward a protective antibody response. In contrast, an inflammatory Th1 response is induced in the presence of DR4. These observations offer an explanation for the differential genetic susceptibility of DR4+ and DR11+ individuals to the development of chronic Lyme arthritis and, eventually, the progression to antibiotic-refractory Lyme arthritis.

HLA-DRB1*08 allele may help to distinguish between type 1 diabetes mellitus and type 2 diabetes mellitus in Mexican children

BACKGROUND

It may be difficult to distinguish type 1 diabetes mellitus (T1DM) from type 2 diabetes mellitus (T2DM) in the pediatric population. Autoantibodies may help to differentiate both types of diabetes, but sometimes these are positive in patients with T2DM and negative in patients with T1DM. The human leukocyte antigen (HLA)-DR genotype has been associated with T1DM and with T2DM only in adults and in determined cases.

AIM

To determine the differences in HLA class II allele frequencies in Mexican children with T1DM and T2DM.

METHODS

We included 72 children with T1DM, 28 children with T2DM, and 99 healthy controls. All were Mexican, and diabetes was diagnosed according to the clinical and laboratory criteria established by the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. The HLA-DRB1 typing was performed using polymerase chain reaction-sequence-specific oligonucleotide probe and polymerase chain reaction sequence-specific primers.

RESULTS

We found an increased frequency of HLA-DRB1*08 and a decreased frequency of HLA-DRB1*04 in the group with T2DM vs. T1DM [p = 0.0001, odds ratio (OR) = 10.58, 95% confidence interval (CI) = 3-40.8 and p = 0.0006, OR = 0.24, 95% CI = 0.11-0.53, respectively]. No significant differences were found between HLA-DRB1 alleles in T2DM vs. controls. In the group with T1DM, there was a significantly increased frequency of the HLA-DR4 and HLA-DR3 alleles relative to controls (p = 0.0000001, OR = 3.59, 95% CI = 2.2-5.8 and p = 0.00009, OR = 4.66, 95% CI = 2.1-10.3, respectively).

CONCLUSION

There are significant differences in the HLA profile in Mexican children with T1DM and T2DM. HLA typing could play a role in the differentiation between both types of diabetes in this population.

A risk assessment tool (OsteoRisk) for identifying Latin American women with osteoporosis

OBJECTIVE

To develop a simple and easy-to-use tool for identifying osteoporotic women (femoral neck bone mineral density [BMD] T-scores<or=-2.5) in Latin America.

DESIGN

Retrospective study involving review of medical records.

SETTING

Osteoporosis clinics in 6 Latin American countries.

PATIENTS

Postmenopausal women ages >or=50 in Latin America who had femoral neck BMD measurements.

MEASUREMENTS AND MAIN RESULTS

A risk index was developed from 1,547 patients based on least square regression using age, weight, history of fractures, and other variables as predictors for BMD T-score. The final model was simplified by reducing the number of predictors; sensitivity and specificity were evaluated before and after reducing the number of predictors to assess performance of the index. The final model included age, weight, country, estrogen use, and history of fractures as significant predictors for T-score. The resulting scoring index achieved 91% sensitivity and 47% specificity. Simplifying the index by using only age and weight yielded similar performance (sensitivity, 92%; specificity, 45%). Three risk categories were identified based on OsteoRisk, the index using only age and body weight: high-risk patients (index <=-2; 65.6% were osteoporotic), moderate-risk patients (-2< index <=1; 26.7% were osteoporotic), and low-risk patients (index>1; 8% were osteoporotic). Similar results were seen in a validation sample of 279 women in Brazil.

CONCLUSION

Age and weight alone performed well for predicting the risk of osteoporosis among postmenopausal women. The OsteoRisk is an easy-to-use tool that effectively targets the vast majority of osteoporotic patients in Latin America for evaluation with BMD.

HLA genotypes in turkish patients with myasthenia gravis: Comparison with multiple sclerosis patients on the basis of clinical subtypes and demographic features

The nature and intensity of the association of myasthenia gravis (MG) with distinct human leukocyte antigens (HLA) haplotypes differ between ethnic populations. The aims of the present study were to examine the relationship between HLA class I and II haplotypes and MG; to show the HLA associations with various MG subsets; and to investigate the association between MG and clinical subgroups of multiple sclerosis (MS) regarding HLA haplotypes. A total of 66 patients with MG were enrolled onto the study. The mean age at onset was 42.01 years. A total of 122 clinically definite MS patients and 188 healthy subjects were examined as control groups. The present study clearly showed associations with HLA-DR3, -B8, -A1, and -A2 in MG. In patients with early-onset MG, associations with HLA-DR3, -B8, and -A2 were stronger. When compared with MS, in the MG group, there was still a strong association with -B8, -DR3, and -A1. In subgroup analysis, there was no difference between MG and primary progressive MS patients. On the basis of the presence of anti-AChR antibodies, there was a statistically significant association with HLA-DR3. On the basis of presence of thymoma, no HLA allele showed clear associations in MG patients with thymoma. This is the first study to examine the relationship between HLA haplotypes and MG in the Turkish population and to compare MG with another autoimmune disease, MS, on the basis of the HLA haplotypes. Further investigations with a larger population are required to explain this finding.