Dog leucocyte antigen (DLA) class II haplotypes and risk of canine diabetes mellitus in specific dog breeds

Background

Canine diabetes mellitus (DM) is a common endocrine disease in domestic dogs. A number of pathological mechanisms are thought to contribute to the aetiopathogenesis of relative or absolute insulin deficiency, including immune-mediated destruction of pancreatic beta cells. DM risk varies considerably between different dog breeds, suggesting that genetic factors are involved and contribute susceptibility or protection. Associations of particular dog leucocyte antigen (DLA) class II haplotypes with DM have been identified, but investigations to date have only considered all breeds pooled together. The aim of this study was to analyse an expanded data set so as to identify breed-specific diabetes-associated DLA haplotypes.

Methods

The 12 most highly represented breeds in the UK Canine Diabetes Register were selected for study. DLA-typing data from 646 diabetic dogs and 912 breed-matched non-diabetic controls were analysed to enable breed-specific analysis of the DLA. Dogs were genotyped for allelic variation at DLA-DRB1, -DQA1, -DQB1 loci using DNA sequence-based typing. Genotypes from all three loci were combined to reveal three-locus DLA class II haplotypes, which were evaluated for statistical associations with DM. This was performed for each breed individually and for all breeds pooled together.

Results

Five dog breeds were identified as having one or more DLA haplotype associated with DM susceptibility or protection. Four DM-associated haplotypes were identified in the Cocker Spaniel breed, of which one haplotype was shared with Border Terriers. In the three breeds known to be at highest risk of DM included in the study (Samoyed, Tibetan Terrier and Cairn Terrier), no DLA haplotypes were found to be associated with DM.

Conclusions

Novel DLA associations with DM in specific dog breeds provide further evidence that immune response genes contribute susceptibility to this disease in some cases. It is also apparent that DLA may not be contributing obvious or strong risk for DM in some breeds, including the seven breeds analysed for which no associations were identified.

Predicting cognitive ability in ageing cohorts using Type 2 diabetes genetic risk

AIMS

To investigate whether there is overlap in the genetic determinants of Type 2 diabetes and cognitive ageing by testing whether a genetic risk score for Type 2 diabetes can predict variation in cognitive function in older people without dementia.

METHODS

Type 2 diabetes genetic risk scores were estimated using various single nucleotide polymorphism significance inclusion criteria from an initial genome-wide association study, the largest in Type 2 diabetes to date. Scores were available for 2775-3057 individuals, depending on the cognitive trait.

RESULTS

Type 2 diabetes genetic risk was associated with self-reported diabetes mellitus. Across varying single nucleotide polymorphism-inclusion levels, a significant association between Type 2 diabetes genetic risk and change in general cognitive function was found (median r = 0.04); however, this was such that higher Type 2 diabetes genetic risk related to higher cognitive scores.

CONCLUSIONS

To investigate more fully the source of the often observed comorbidity between Type 2 diabetes and cognitive impairment, one direction for future research will be to use cognitive ability polygenic risk scores to predict Type 2 diabetes in line with the reverse causation hypothesis that people with lower pre-morbid cognitive ability are more likely to develop Type 2 diabetes.

Major histocompatibility complex diversity in the endangered Ethiopian wolf (Canis simensis)

The major histocompatibility complex (MHC) influences immune response to infection and vaccination. In most species, MHC genes are highly polymorphic, but few wild canid populations have been investigated. In Ethiopian wolves, we identified four DLA (dog leucocyte antigen)-DRB1, two DLA-DQA1 and five DQB1 alleles. Ethiopian wolves, the world's rarest canids with fewer than 500 animals worldwide, are further endangered and threatened by rabies. Major rabies outbreaks in the Bale Mountains of southern Ethiopia (where over half of the Ethiopian wolf population is located) have killed over 75% of wolves in the affected sub-populations. In 2004, following a rabies outbreak, 77 wolves were vaccinated, and 19 were subsequently recaptured to monitor the effectiveness of the intervention. Pre- and post-vaccination rabies antibody titres were available for 18 animals, and all of the animals sero-converted after vaccination. We compared the haplotype frequencies of this group of 18 with the post-vaccination antibody titre, and showed that one haplotype was associated with a lower response (uncorrected P < 0.03). In general, Ethiopian wolves probably have an adequate amount of MHC variation to ensure the survival of the species. However, we sampled only the largest Ethiopian wolf population in Bale, and did not take the smaller populations further north into consideration.

Insights into the genetic architecture of osteoarthritis from stage 1 of the arcOGEN study

Objectives

The genetic aetiology of osteoarthritis has not yet been elucidated. To enable a well-powered genome-wide association study (GWAS) for osteoarthritis, the authors have formed the arcOGEN Consortium, a UK-wide collaborative effort aiming to scan genome-wide over 7500 osteoarthritis cases in a two-stage genome-wide association scan. Here the authors report the findings of the stage 1 interim analysis.

Methods

The authors have performed a genome-wide association scan for knee and hip osteoarthritis in 3177 cases and 4894 population-based controls from the UK. Replication of promising signals was carried out in silico in five further scans (44 449 individuals), and de novo in 14 534 independent samples, all of European descent.

Results

None of the association signals the authors identified reach genome-wide levels of statistical significance, therefore stressing the need for corroboration in sample sets of a larger size. Application of analytical approaches to examine the allelic architecture of disease to the stage 1 genome-wide association scan data suggests that osteoarthritis is a highly polygenic disease with multiple risk variants conferring small effects.

Conclusions

Identifying loci conferring susceptibility to osteoarthritis will require large-scale sample sizes and well-defined phenotypes to minimise heterogeneity.

Autoantibodies to a 140-kd protein in juvenile dermatomyositis are associated with calcinosis

OBJECTIVE

The identification of novel autoantibodies in juvenile dermatomyositis (DM) may have etiologic and clinical implications. The aim of this study was to describe autoantibodies to a 140-kd protein in children recruited to the Juvenile DM National Registry and Repository for UK and Ireland.

METHODS

Clinical data and sera were collected from children with juvenile myositis. Sera that recognized a 140-kd protein by immunoprecipitation were identified. The identity of the p140 autoantigen was investigated by immunoprecipitation/immunodepletion, using commercial monoclonal antibodies to NXP-2, reference anti-p140, and anti-p155/140, the other autoantibody recently described in juvenile DM. DNA samples from 100 Caucasian children with myositis were genotyped for HLA class II haplotype associations and compared with those from 864 randomly selected UK Caucasian control subjects.

RESULTS

Sera from 37 (23%) of 162 patients with juvenile myositis were positive for anti-p140 autoantibodies, which were detected exclusively in patients with juvenile DM and not in patients with juvenile DM-overlap syndrome or control subjects. No anti-p140 antibody-positive patients were positive for other recognized autoantibodies. Immunodepletion suggested that the identity of p140 was consistent with NXP-2 (the previously identified MJ autoantigen). In children with anti-p140 antibodies, the association with calcinosis was significant compared with the rest of the cohort (corrected P < 0.005, odds ratio 7.0, 95% confidence interval 3.0-16.1). The clinical features of patients with anti-p140 autoantibodies were different from those of children with anti-p155/140 autoantibodies. The presence of HLA-DRB1*08 was a possible risk factor for anti-p140 autoantibody positivity.

CONCLUSION

This study has established that anti-p140 autoantibodies represent a major autoantibody subset in juvenile DM. This specificity may identify a further immunogenetic and clinical phenotype within the juvenile myositis spectrum that includes an association with calcinosis.

The protein tyrosine phosphatase N22 gene is associated with juvenile and adult idiopathic inflammatory myopathy independent of the HLA 8.1 haplotype in British Caucasian patients

OBJECTIVE

To examine single-nucleotide polymorphisms (SNPs) of the protein tyrosine phosphatase N22 gene (PTPN22) and to study the relationship between PTPN22 and the HLA region in patients with idiopathic inflammatory myopathies (IIMs).

METHODS

PTPN22 SNPs were assessed in a large, cross-sectional, case-control study from the UK involving patients with adult or juvenile IIM, comprising patients with polymyositis (PM) (n=114), dermatomyositis (DM) (n=102), myositis associated with another connective tissue disease (myositis-CTD overlap syndrome) (n=64), or juvenile DM (n=101), in comparison with 748 control subjects. Seventeen PTPN22 SNPs were genotyped using the Sequenom MassArray iPLEX platform. Serotyping for myositis-specific/myositis-associated autoantibodies (MSAs/MAAs) was performed by radioimmunoprecipitation.

RESULTS

A significant association was noted between the R620W variant (rs2476601) and IIM (corrected P [Pcorr]=0.0009 versus controls), and specifically with the clinical subgroup of PM (Pcorr=0.003 versus controls). A weaker association was noted with juvenile DM (Pcorr=0.009 versus controls). No significant associations were noted after stratification by serologic subgroups. The association with the R620W variant was independent of alleles forming the HLA 8.1 haplotype. No other PTPN22 SNPs were associated with IIM. The PTPN22 haplotype containing the R620W T allele was the only haplotype significantly associated with IIM.

CONCLUSION

The R620W variant is a significant risk factor for IIM, independent of the HLA 8.1 haplotype. Unlike that in the HLA region, risk is not increased in individuals possessing MSAs/MAAs. These results are further evidence that the PTPN22 gene confers autoimmune susceptibility.

Levels of 5' RNA tags in plasma and buffy coat from EDTA blood increase with time

BACKGROUND

For biological sample banking it is important to precisely document sample treatment prior to extraction and storage. A major variable is the interval between blood sampling and subsequent processing and storage. We have determined the relationship between this time interval and frequency of 5' transcript tags. This study was designed to establish guidelines for collecting RNA from blood in prospective studies and ensure maximum availability of RNA analytes.

METHODS

Venous blood was collected from 40 healthy volunteers. Samples were processed immediately, 12, 24 and 36 h post collection and buffy coat and/or plasma removed. Total RNA was extracted and reverse transcribed, assays were optimized and levels of 5' RNA tags quantified by qPCR.

RESULTS

Stably expressed reference genes were selected to examine 5' tags in plasma and buffy coat blood fractions. Whole blood was processed at various time points post collection to determine the affect on the presence and stability of 5' RNA tags. A significant increase (P < 0.05 to P < 0.001) in 5' RNA tags was observed at 12 h and up to 36 h in plasma and buffy coat samples isolated from EDTA blood which was maintained at 4 degrees C prior to processing when compared with plasma and buffy coat isolated from EDTA blood processed immediately.

CONCLUSIONS

Over time 5' RNA tags increase in both plasma and buffy coat samples. It has been previously shown that removing cells from their normal environment produces cellular activation and up-regulation of pathways resulting in increased transcript expression. Positive correlation was observed between the time interval from sample collection to storage and amount of 5' transcript tags present. This increase could be due to white blood cells undergoing necrosis and lysis, or from RNA protected within apoptotic bodies. As 5' RNA tags were targeted using random primers for reverse transcription, even RNA partly degraded by RNases would have been detected.

Gene expression profiling of normal and ruptured canine anterior cruciate ligaments

OBJECTIVE

To identify genes which may be involved in the development of anterior cruciate ligament (ACL) laxity and rupture in a naturally occurring canine osteoarthritis (OA) model.

DESIGN

Three groups of dog were studied: (1) dogs with ACL rupture; (2) dogs with intact ACLs from a breed predisposed to ACL rupture; (3) dogs with intact ACLs from a breed at very low risk of rupture. The transcriptomes of the ACLs from each group were compared using a whole genome microarray and quantitative reverse transcriptase polymerase chain reaction. Differential gene expression in ruptured canine ACLs was compared with that published in the literature for ruptured human ACLs.

RESULTS

No significant differences were identified between the gene expression profiles of normal ACLs of a breed predisposed to ACL rupture when compared to a breed relatively resistant to ACL rupture. A general pattern of increased protease and extracellular structural matrix gene expression was identified in the ruptured ACLs when compared to intact ACLs. The gene expression profiles of ruptured canine ACLs demonstrate similar patterns to those previously reported for ruptured human ACLs.

CONCLUSIONS

A transcriptomic basis to breed specific risk for the development of canine ACL rupture was not identified. Although changes in matrix associated gene expression in the ruptured ACL are similar between humans and dogs, the molecular events which may predispose to ACL laxity and rupture were not defined.

Major histocompatibility complex typing of dogs from Russia shows further dog leukocyte antigen diversity

Blood samples from 85 Russian dogs and wolves were collected as dried blood spots on paper and transported to the UK by mail. We obtained partial or complete three-locus canine major histocompatibility complex [dog leukocyte antigen (DLA)] class II haplotypes on 81 of these samples. Six new alleles were identified: three DLA-DRB1 and three DLA-DQB1. These alleles occurred in haplotypic combinations not previously seen in other European dogs. One haplotype appeared to lack a DQB1 allele. Two of the new haplotypes segregated through a family of dogs that was investigated.

Risk of anal furunculosis in German shepherd dogs is associated with the major histocompatibility complex

Anal furunculosis (AF) is a chronic, progressive inflammatory disease of the perianal tissues most frequently affecting middle-aged or older German Shepherd dogs (GSD). Because this breed accounts for over 80% of all reported cases, there is likely to be a genetic association with disease susceptibility. Although there are some similarities with perianal fistulation that occurs in human Crohn's disease, the aetiology and pathogenesis of AF are still poorly understood. Recent research has suggested an immune-mediated aetiology, and evidence for this has been further provided by clinical responses to the immunosuppressive drug cyclosporin. The aim of the current study was to investigate canine major histocompatibility complex immune response genes. Dog leucocyte antigen class II alleles and haplotypes were characterised by sequence-based typing of 107 GSD affected with AF and 196 breed-matched controls collected in the UK. A highly significant association of DLA-DRB1*00101 with the presence of AF was observed (OR = 5.01, CI = 2.7-9.3, P < 0.00000001). This association was confirmed in a second cohort of GSD collected in Finland. Homozygosity for this allele is associated with an earlier disease onset.

Genetic susceptibility to total hip arthroplasty failure: a preliminary study on the influence of matrix metalloproteinase 1, interleukin 6 polymorphisms and vitamin D receptor

BACKGROUND

Matrix metalloproteinase (MMP)1, interleukin(IL)6 and vitamin D receptor (VDR) have been implicated in the biological cascade of events initiated by particulate wear debris and bacterial infection, resulting in periprosthetic bone loss around loosened total hip replacements (THRs). The individual responses to such stimuli may be dictated by genetic variation.

OBJECTIVE

To study the effect of single-nucleotide polymorphisms (SNPs) within these candidate genes.

METHODS

A case-control study of the MMP1, IL6 and VDR genes was performed for possible association with deep sepsis or aseptic loosening. All cases included in the study were Caucasian patients with osteoarthritis who had received a cemented Charnley total hip arthroplasty (THA) and polyethylene acetabular cup. Cases consisted of 91 patients with early aseptic loosening and 71 patients with microbiological evidence of deep infection on surgery. Controls consisted of 150 patients with THAs that were clinically asymptomatic for over 10 years and showed no radiographic features of aseptic loosening. DNA samples from all individuals were genotyped using Taqman allelic discrimination.

RESULTS

The C allele (p = 0.001; OR = 3.27; 95% CI 2.21 to 4.83) and C/C genotype (p = 0.001) for the MMP1 SNP were highly associated with aseptic failure when compared with controls. No statistically significant relationships were found between aseptic loosening and the MMP2, MMP4, IL6 -174 or VDRL SNPs. The T allele (p = 0.007; OR = 1.76; 95% CI 1.16 to 2.66) and T/T genotype (p = 0.028) for VDR-T were statistically associated with osteolysis owing to deep infection as compared with controls. No statistically significant relationship was found between septic failure and any of the other SNPs examined in this study.

CONCLUSIONS

Aseptic loosening and possibly deep infection of THR may be due to the genetic influence of candidate susceptibility genes. SNP markers may serve as predictors of implant survival and aid in pharmacogenomic prevention of THR failure.

Canine diabetes mellitus: from phenotype to genotype

Breed differences in susceptibility to diabetes mellitus in dogs suggest an underlying genetic component to the pathogenesis of the disease. There is little evidence for an equivalent of human type 2 diabetes in dogs, and it has been proposed that canine diabetes is more comparable to the type 1 form of the disease. Certain immune response genes, particularly those encoding major histocompatibility complex molecules involved in antigen presentation, are important in determining susceptibility to human type 1 diabetes. We tested the hypothesis that canine major histocompatibility complex genes (known as the dog leucocyte antigen) are associated with diabetes in dogs. A total of 530 diabetic dogs and more than 1000 controls were typed for dog leucocyte antigen, and associations were found with three specific haplotypes. The DLA-DRB1*009/DQA1*001/DQB1*008 haplotype shows the strongest association with diabetes in the UK dog population. This haplotype is common in diabetes-prone breeds (Samoyed, cairn terrier and Tibetan terrier) but rare in diabetes-resistant breeds (boxer, German shepherd dog and golden retriever), which could explain differences in the prevalence of diabetes in these different breeds. There is evidence that the DLA-DQA1*001 allele is also associated with hypothyroidism, suggesting that this could represent a common susceptibility allele for canine immune-mediated endocrinopathies.

Endothelial nitric oxide synthase polymorphisms in biopsy-proven erythema nodosum from a defined population

OBJECTIVE

To assess the potential in-fluence of endothelial nitric oxide synthase (eNOS) polymorphisms in the susceptibility to and clinical expression of a series of patients diagnosed with biopsy-proven erythema nodosum (EN).

METHODS

Ninety-seven unselected patients from Northwest Spain with biopsy-proven EN were studied. Patients and ethnically matched controls were genotyped by PCR based techniques for a variable number tandem repeat polymorphism in intron 4, a T/C polymorphism at position -786 in the promoter region and a polymorphism in exon 7 (298Glu/Asp or 5557G/T) of the eNOS gene.

RESULTS

No differences in allele or genotype frequencies for any of the individual eNOS polymorphisms were observed between biopsy-proven patients with EN and controls. It was also the case when patients with EN secondary to sarcoidosis were compared with the remaining patients or controls. In the group of patients with EN, no linkage disequilibrium between these polymorphisms was found. Also, no significant differences in haplotype frequencies were observed between patients and controls.

CONCLUSION

Our present results do not support a role for eNOS polymorphisms in the susceptibility to and clinical expression of EN.

Tumour necrosis factor-alpha single nucleotide polymorphisms are not independent of HLA class I in UK Caucasians with adult onset idiopathic inflammatory myopathies

OBJECTIVE

To investigate haplotype tagging single nucleotide polymorphisms (SNPs) in the tumour necrosis factor alpha (TNF-alpha) gene, in UK Caucasian idiopathic inflammatory myopathy (IIM) patients.

METHODS

A cross-sectional, case-control study of four TNF-alpha SNPs was undertaken, comparing cases of polymyositis (PM) (n = 121), dermatomyositis (DM) (n = 109) and myositis overlapping with other connective tissue diseases (CTD-overlap) (n = 73) with normal subjects (n = 177). Subgroup analyses were undertaken after stratifying for myositis specific/associated antibodies.

RESULTS

The TNF-308A allele demonstrated a strong association with each myositis disease subgroup vs controls [PM, odds ratio (OR) 2.8, 95% confidence interval 1.9-4.3; DM, OR 2.5, 1.6-3.8; CTD-overlap, OR 3.3, 2.1-5.1]. The TNF-308GA/AA genotype frequency was significantly increased vs controls (PM, OR 3.7, 2.1-6.3; DM, OR 3.2, 1.8-5.5; CTD-overlap, OR 5.0, 2.6-9.6) suggesting a dominant model. The association was strongest in patients possessing anti-aminoacyl transfer RNA synthetase (anti-synthetase) (OR 5.1, 3.3-8.0) or -PM-Scl (OR 5.0, 2.7-8.9) antibodies. The -1031T allele was also a significant risk factor in DM (OR 2.2, 1.4-3.6), anti-synthetase (OR 2.9, 1.6-5.3) and -PM-Scl (OR 5.6, 1.9-6.4) antibody positive patients. The TNF-308A association was lost after adjusting for HLA-B*08, but remained independent of HLA-DQB1*02 (both are alleles forming part of the common ancestral haplotype). The HLA-B*08/TNF-308A/DRB1*03/DQA1*05/DQB1*02 haplotype was a risk factor in all myositis subgroups vs controls (OR 3.0, 1.8-5.3).

CONCLUSIONS

TNF-308A and -1031T alleles are significant risk factors in the IIMs. In the IIMs, the TNF-308A allele is part of the common ancestral haplotype, but is not independent of HLA-B*08.

Canine DLA diversity: 1. New alleles and haplotypes

The aim of this component was to establish the range of DLA diversity in as many dog breeds as possible. In particular, we wanted to collect breeds that had not previously been studied. Data were submitted of 937 dogs of over 80 different breeds, and these included 17 'new' breeds. Twenty-eight new alleles were identified including 21 DLA-DRB1, 2 DLA-DQA1 and 5 DLA-DQB1 alleles. These occurred in many new haplotype combinations. One haplotype was identified that appeared to lack DQB1. Two other haplotypes carry two DQB1 genes. It was clear that each dog breed has a restricted range of DLA alleles and haplotypes, and no breed had all 88 haplotypes identified in this study.

Association of DRB1 shared epitope genotypes with early mortality in rheumatoid arthritis: results of eighteen years of followup from the early rheumatoid arthritis study

OBJECTIVE

To determine whether the HLA-DRB1 shared epitope (SE) is associated with early mortality and specific causes of death in rheumatoid arthritis (RA).

METHODS

HLA-DRB1 genotyping was carried out on blood samples from 767 patients recruited for the Early RA Study (ERAS), a multicenter, inception cohort study with followup over 18 years. Dates and causes of death (n = 186) were obtained from the Office of National Statistics. The association of HLA-DRB1 alleles with risk of mortality was assessed using Cox proportional hazards regression analyses. Multivariate stepwise models were used to assess the predictive value of HLA-DRB1 genotypes compared with other potential baseline risk factors.

RESULTS

The SE was not significantly associated with overall mortality. However, the presence of 2 SE alleles was associated with risk of mortality from ischemic heart disease (hazard ratio [HR] 2.02 [95% confidence interval 1.04-3.94], P = 0.04), and malignancy (HR 2.18 [95% confidence interval 1.17-4.08], P = 0.01). Analysis of specific SE genotypes (corrected for age and sex) revealed that the HLA-DRB1*0101/*0401 and 0404/*0404 genotypes were the strongest predictors of mortality from ischemic heart disease (HR 5.11 and HR 7.55, respectively), and DRB1*0101/*0401 showed a possible interaction with smoking. Male sex, erythrocyte sedimentation rate, and Carstairs Deprivation Index were also predictive, but the Health Assessment Questionnaire score, rheumatoid factor, nodules, and swollen joint counts were not. Mortality due to malignancy was particularly associated with DRB1*0101 genotypes.

CONCLUSION

The risk of mortality due to ischemic heart disease or cancer in RA is increased in patients carrying HLA-DRB1 genotypes with particular homozygous and compound heterozygous SE combinations.

Canine DLA diversity: 2. Family studies

The canine Major Histocompatibility Complex is referred to as DLA (for dog leukocyte antigen). There are no published studies on DLA segregation in the dog, so this part of the DLA workshop aimed to collect DNA from multigeneration families of different breeds of dogs. Twenty-two families of dogs were submitted to the workshop, comprising 313 individuals, of which 247 had one or both parents available.

Canine DLA diversity: 3. Disease studies

There are many millions of dogs worldwide, and these dogs have many different functions. The most obvious use is providing companionship, but there are also many working dogs, including guide dogs for the blind, hearing dogs, guard dogs and farm dogs, to mention a few. The health and welfare of these dogs is of great concern to dog owners, dog breeders and to those who use dogs in their work. Dogs spontaneously develop many diseases that are very similar to their human counterparts. Dogs may, therefore, provide exceptional animal models for such diseases. Identifying genetic markers in the dog may be easier than in humans, and may then provide useful information about genes that can be transferred to humans. This study looked for associations between DLA and two autoimmune diseases of the dog, diabetes and hypothyroidism. DLA associations were found for both of these diseases.

Lack of association between interleukin-6 promoter polymorphism at position -174 and Henoch-Schönlein pur pura

OBJECTIVE

To assess whether polymorphism of the interleukin (IL)-6 gene at the position -174 was implicated in the incidence of Henoch-Schönlein pur-pura (HSP). A further objective was to determine if any relationship existed with severe systemic complications of HSP, in particular with severe renal and gastrointestinal involvement.

METHODS

Unselected patients from Northwest Spain with primary cutaneous vasculitis classified as HSP according to proposed criteria were studied. All patients included in the present study were required to have had at least 2 year's follow-up. Patients and controls were genotyped for a single biallelic (G/C) nucleotide polymorphism in the promoter region at the position -174 of the IL-6 gene by a polymerase reaction chain-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

Forty-six Caucasian HSP patients and 124 healthy matched controls were studied. No allele or genotype differences between the whole group of HSP and controls were observed. This was also the case when HSP patients were stratified by the presence of gastrointestinal complications, nephritis, and permanent renal involvement (renal sequelae).

CONCLUSION

The polymorphism in IL-6 gene promoter (-174 G/C) does not appear to be a genetic risk factor for HSP in Northwest Spain.

Association of a common dog leucocyte antigen class II haplotype with canine primary immune-mediated haemolytic anaemia

Immune-mediated haemolytic anaemia (IMHA) is the commonest immune-mediated disease of the dog, representing a major health concern to this species. The aim of this investigation was to determine whether genetic susceptibility to IMHA is associated with genes of the canine major histocompatibility complex (MHC; dog leucocyte antigen system, DLA). Samples were collected from 108 dogs with primary idiopathic, Coombs' positive IMHA. This diseased population was subdivided on the basis of Coombs' test results into two groups: 1) dogs with dominant warm-reactive immunoglobulin (Ig) G haemagglutinins and (2) dogs with an additional or dominant cold-reactive IgM haemagglutinin. The DLA class II alleles and haplotypes of the diseased population were characterised, and these data were compared with those derived from a breed-matched control cohort and a much larger group of DLA-typed dogs. Two haplotypes were increased in the patient group: DLA-DRB1*00601/DQA1*005011/DQB1*00701 (in the group with warm-reactive IgG haemagglutinins only) and DLA-DRB1*015/DQA1*00601/DQB1*00301 (in both groups, but more so in the group with cold-reactive IgM haemagglutinins). One haplotype, DLA-DRB1*001/DQA1*00101/DQB1*00201, was decreased in the total patient group, but this decrease was limited to the warm-reactive IgG haemagglutinins group, and it was actually increased in the cold-reactive IgM haemagglutinins group. A second haplotype, DLA-DRB1*015/DQA1*00601/DQB1*02301, was also decreased in the total patient group, and this decrease was found in both subgroups. In addition, all haplotypes carrying DLA-DRB1*001 were significantly increased in the cold-reactive IgM haemagglutinins group. When the overall patient group was divided on the basis of individual breeds with more than six animals represented, each of the haplotypes could be shown to be implicated in one of the breeds. Thus, it was apparent that different breeds had different MHC associations with canine IMHA, which is similar to the observation that different human ethnic groups can have different HLA associations with the same immune-mediated disease.

Identification of susceptibility and protective major histocompatibility complex haplotypes in canine diabetes mellitus

Diabetes mellitus occurs spontaneously in dogs, which is believed to have an autoimmune component and to be a model of human latent autoimmune diabetes of adults (LADA). Some dog breeds (e.g. Samoyed) are particularly predisposed, whereas others (e.g. Boxer) are highly resistant. With the completion of the Dog Genome Assembly, comparative genomic studies of complex diseases in dogs, including diabetes, could provide an important investigative approach into such disorders. Type 1 diabetes in humans is strongly associated with major histocompatibility complex (MHC) class II polymorphisms. We have investigated whether canine dog leucocyte antigen (DLA) class II haplotypes are associated with diabetes. DNA from 460 cases and 1047 controls were genotyped for DLA-DRB1, DLA-DQA1 and DLA-DQB1 using sequence-based typing. Three DLA haplotypes, DRB1*009/DQA1*001/DQB1*008, DRB1*015/DQA1*0061/DQB1*023 and DRB1*002/DQA1*009/DQB1*001, were found at significantly increased frequency in cases with diabetes compared with controls. One DLA-DQ haplotype, DQA1*004/DQB1*013, was significantly reduced in cases with diabetes. Further analysis showed that DQA1 alleles carrying arginine at codon 55 of DQA1 were increased in dogs with diabetes. To our knowledge, this is the first report of a comparative study of MHC and diabetes in a non-rodent species. Since no laboratory model of LADA exists and dogs and humans share similar environments, further research into canine diabetes is warranted.

Monocyte chemotactic protein-1 single nucleotide polymorphisms do not confer susceptibility for the development of adult onset polymyositis/dermatomyositis in UK Caucasians

OBJECTIVES

Polymyositis (PM) and dermatomyositis (DM) form part of the idiopathic inflammatory myopathies (IIMs). The chemokine monocyte chemotactic protein-1 (MCP-1) is expressed at sites of the T cell inflammatory response in the IIMs. We thus investigate whether genetic markers in the MCP-1 gene confer disease susceptibility for the development of PM and DM.

METHODS

DNA samples were analysed from a group of 195 UK Caucasian IIM patients, comprising 103 PM and 92 DM. Their results were compared with those of 162 ethnically matched controls. The polymorphic positions of three single nucleotide polymorphisms (SNPs) and one insertion-deletion sequence within regions coding for MCP-1 were tested. The SNPs examined were located in intron 1 (rs2857657, C/G), exon 2 (rs4586, A/G) and the 3 ' untranslated region (rs13900, C/T). The insertion-deletion sequence was located in intron 1 (rs3917887, AGCTCCTCCTTCTC/-). Each SNP was tested for Hardy-Weinberg equilibrium and allelic/genotypic associations. Haplotype frequencies were estimated using the Expectation/Maximization algorithm.

RESULTS

There was strong linkage disequilibrium present between three out of these four markers. The majority of controls were in Hardy Weinberg equilibrium. No allelic, genotypic or haplotypic associations were detected when comparing PM or DM cases to controls, or when PM and DM were compared with each other.

CONCLUSIONS

Genetic markers in the MCP-1 gene do not demonstrate significant genetic associations with the IIMs, and do not discriminate PM from DM in a UK Caucasian population.

Lack of association between macrophage migration inhibitory factor gene (-173 G/C) polymorphism and cutaneous vasculitis

OBJECTIVE

To assess whether polymorphism of the macrophage migration inhibitory factor (MIF) gene at position -173 was implicated in the incidence of Henoch-Schönlein purpura (HSP) and cutaneous leukocytoclastic angiitis (CLA). A further objective was to determine if any relationship existed with severe systemic complications of HSP, in particular with severe renal involvement and permanent renal dysfunction.

METHODS

Unselected patients from Northwest Spain with primary cutaneous vasculitis classified as HSP or hypersensitivity vasculitis (HV) according to proposed criteria were studied. Patients with HV were included in this study if they fulfilled the Chapel Hill Consensus Conference on the Nomenclature of Systemic Vasculitis definitions for CLA. Patients and controls were genotyped for a single nucleotide polymorphism (SNP) in the 5'-flanking region at position -173 of the MIF gene, using SNapshot ddNTP primer extension, followed by capillary electrophoresis (ABI 3100).

RESULTS

Ninety-five Caucasian patients (57 classified as having HSP and 38 who fulfilled definitions for CLA) and 122 healthy controls were studied. No allele or genotype differences between the whole group of HSP or CLA patients and controls were observed. This was also the case when HSP patients were stratified by the presence of gastrointestinal complications, nephritis, and permanent renal involvement (renal sequelae).

CONCLUSION

The polymorphism in MIF gene promoter (-173 G/C) does not appear to be genetic risk factors for cutaneous vasculitis in Northwest Spain.

Association of canine hypothyroidism with a common major histocompatibility complex DLA class II allele

Dogs exhibit a range of immune-mediated conditions including a lymphocytic thyroiditis which has many similarities to Hashimoto's thyroiditis in man. We have recently reported an association in Doberman Pinschers between canine hypothyroidism and a rare DLA class II haplotype that contains the DLA-DQA1*00101 allele. We now report a further series of 173 hypothyroid dogs in a range of breeds where a significant association with DLA-DQA1*00101 is shown.

APOE epsilon variation in multiple sclerosis susceptibility and disease severity: some answers

BACKGROUND

Previous studies have examined the role of APOE variation in multiple sclerosis (MS), but have lacked the statistical power to detect modest genetic influences on risk and disease severity. The meta- and pooled analyses presented here utilize the largest collection, to date, of MS cases, controls, and families genotyped for the APOE epsilon polymorphism.

METHODS

Studies of MS and APOE were identified by searches of PubMed, Biosis, Web of Science, Cochrane Review, and Embase. When possible, authors were contacted for individual genotype data. Meta-analyses of MS case-control data and family-based analyses were performed to assess the association of APOE epsilon genotype with disease risk. Pooled analyses of MS cases were also performed to assess the influence of APOE epsilon genotype on disease severity.

RESULTS

A total of 22 studies (3,299 MS cases and 2,532 controls) were available for meta-analysis. No effect of epsilon2 or epsilon4 status on MS risk was observed (summary OR 1.14, 95% CI 0.96-1.34 and OR 0.89, 95% CI 0.78-1.01). Results obtained from analyses of APOE genotypes in 1,279 MS families were also negative (p = 0.61). Finally, results from pooled analyses of 4,048 MS cases also argue strongly that APOE epsilon status does not distinguish a relapsing-remitting from primary progressive disease course, or influence disease severity, as measured by the Expanded Disability Status Scale and disease duration.

CONCLUSION

Overall, these findings do not support a role for APOE in multiple sclerosis, and underscore the importance of using large sample sizes to detect modest genetic effects, particularly in studies of genotype-phenotype relationships.

Mitochondrial mutation detection using enhanced multiplex denaturing high-performance liquid chromatography

In this study, we investigated the presence of mutations within the mitochondrial genome in 40 Caucasian subjects using an enhanced multiplex denaturing high-performance liquid chromatography (DHPLC) approach. The enhanced DHPLC approach has increased sensitivity and throughput, and reduced analysis time per individual sample compared to conventional methods. This technique involved amplifying the mitochondrial genome in 18 fragments ranging in size from 300 to 2000 bp using a novel proofreading polymerase (Optimase, Transgenomic Inc., Omaha, NE) with a low misincorporation rate. Fourteen of these fragments underwent subsequent restriction digestion using a combination of five restriction enzymes to enable multiplex DHPLC analysis; the remaining four underwent conventional DHPLC. Using this complete mitochondrial genome-screening approach, we confirmed a number of previously reported mutations and additionally identified a large number of novel mutations using an enhanced DHPLC technique.

TNF-alpha SNP haplotype frequencies in equidae

Tumour necrosis factor alpha (TNF-alpha) is a pro-inflammatory cytokine that plays a crucial role in the regulation of inflammatory and immune responses. In all vertebrate species the genes encoding TNF-alpha are located within the major histocompatability complex. In the horse TNF-alpha has been ascribed a role in a variety of important disease processes. Previously two single nucleotide polymorphisms (SNPs) have been reported within the 5' un-translated region of the equine TNF-alpha gene. We have examined the equine TNF-alpha promoter region further for additional SNPs by analysing DNA from 131 horses (Equus caballus), 19 donkeys (E. asinus), 2 Grant's zebras (E. burchellii boehmi) and one onager (E. hemionus). Two further SNPs were identified at nucleotide positions 24 (T/G) and 452 (T/C) relative to the first nucleotide of the 522 bp polymerase chain reaction product. A sequence variant at position 51 was observed between equidae. SNaPSHOT genotyping assays for these and the two previously reported SNPs were performed on 457 horses comprising seven different breeds and 23 donkeys to determine the gene frequencies. SNP frequencies varied considerably between different horse breeds and also between the equine species. In total, nine different TNF-alpha promoter SNP haplotypes and their frequencies were established amongst the various equidae examined, with some haplotypes being found only in horses and others only in donkeys or zebras. The haplotype frequencies observed varied greatly between different horse breeds. Such haplotypes may relate to levels of TNF-alpha production and disease susceptibility and further investigation is required to identify associations between particular haplotypes and altered risk of disease.

Genetic susceptibility to hip arthroplasty failure--association with the RANK/OPG pathway

The OPG/RANK/RANKL system has been implicated in the biological cascade of events initiated by particulate wear debris and bacterial infection resulting in periprosthetic bone loss around total hip arthroplasties (THA). Individual responses to such stimuli may be dictated by genetic variation caused by single nucleotide polymorphisms (SNPs). Case control study of the osteoprotegerin and RANK genes for possible association with deep sepsis or aseptic loosening. All patients were Caucasian and had had a cemented Charnley THA and polyethylene acetabular cup. Cases consisted of 91 patients with early aseptic loosening and 71 patients with deep infection. Controls were 150 clinically and radiologically well-fixed THAs. DNA samples were genotyped using Taqman allelic discrimination. The A allele (p<0.001) and genotype A/A (p<0.001) for the OPG-163 SNP were associated with aseptic failure. Additionally, the RANK +575 (C/T SNP) T allele (p=0.004) and T/T genotype (p=0.008) frequencies were associated with aseptic failure. Comparing the septic group with the controls, the frequency of the A allele (p<0.001) and the genotype A/A (p<0.001) for the OPG-163 SNP were statistically significant. Aseptic loosening and deep infection of THA may be under the influence of susceptibility genes. SNP markers may serve as predictors of implant survival.

Canine DNA subjected to whole genome amplification is suitable for a wide range of molecular applications

Molecular and genetic studies of canine disease phenotypes can be limited by the amount of DNA available for analysis. New methods have been developed to amplify the genomic DNA of a species producing large quantities of DNA from small starting amounts. Whole genome amplification (WGA) of DNA is now being used in human studies, although this technique has not been applied extensively in veterinary research. We evaluated WGA of canine DNA for suitability in a range of molecular tests. DNA from 93 canine blood extracted and 18 buccal swab samples was subjected to WGA using the GenomiPhi kit (Amersham). Genomic DNA was compared with WGA product using a range of techniques, including reference strand-mediated conformation analysis, denaturing high-performance liquid chromatography analysis, microsatellite genotyping, direct DNA sequencing, and single nucleotide polymorphism allelic discrimination. All samples amplified well, giving an average yield of 3 mug of DNA from 2.5 ng of starting material. Extremely high levels of experimental reproducibility and concordance were observed between source and WGA DNA samples for all analyses used: greater than 95% for blood extracted DNA and greater than 80% for buccal swab DNA. These studies clearly demonstrate the usefulness of WGA of canine DNA as a means of increasing DNA quantities for canine studies. This technique will have major implications for future veterinary research.

High-Resolution Characterization of the Canine DLA-DRB1 Locus Using Reference Strand-Mediated Conformational Analysis

Several methods exist for genotyping class II DLA gene polymorphisms in the dog. The most accurate method is sequence-based typing, which involves direct sequencing of polymerase chain reaction products. However, this method is expensive and unsuitable for large-scale studies. Recently, reference strand-mediated conformation analysis (RSCA) has been shown to be effective for characterizing major histocompatibility complex genes in humans, sheep, horse, and cats. RSCA is a cheap and rapid method, ideal for large epidemiological studies. We have developed RSCA for typing DLA-DRB1 in the dog. Control panels including dogs typed by sequence-based typing and cloned major histocompatibility complex class II alleles in plasmids were used to establish migration patterns for each allele using 20 different fluorescent labeled references, of which 5 were selected to allow for clear identification and discrimination of all known DLA-DRB1 alleles. We have compared 168 dogs typed by RSCA for DLA-DRB1 and characterized by sequence-based typing, with less than 1% discrepancy. These differences were due to missing alleles because of a weak polymerase chain reaction. To date, we have RSCA-typed 1,394 dogs. RSCA is likely to become the method of choice for characterizing DLA genes in the dog and will prove a useful tool for dissecting the immune response of dogs in clinical studies.

Genetic susceptibility to keloid disease: mutation screening of the TGFβ3 gene

Keloid disease (KD) is a fibroproliferative dermal tumour of unknown aetiology. The increased familial clustering in KD, its increased prevalence in certain races and its presence in identical twins suggest a strong genetic predisposition to keloid formation. Transforming growth factor beta isoforms (TGFbeta) play a central role in wound healing and fibrosis and have been implicated in KD pathogenesis. Recent data has suggested that TGFbeta(3) has an important role in scar formation. There is little known about the genetic variation present within the TGFbeta(3) gene, which contains seven exons and six introns spanning 43,000 base pairs of the human genome. Exons one to seven and the promoter region (1000 bp upstream from exon 1 in the 5'-flanking regions) were screened in 95 Caucasian KD cases and 95 Caucasian controls for the presence of novel mutations using a high throughput DHPLC mutation detection technology. There were no mutations identified in any of the exonic regions, however, multiple nondisease associated mutations were found in the promoter region of the TGFbeta(3) gene. These data demonstrate that there is no association between the exonic and promoter regions of TGFbeta(3) gene and keloid scarring in our cohort of Caucasian patients.

Polymorphisms in the endothelial nitric oxide synthase gene are associated with Behçet's disease

OBJECTIVE

Reduced plasma nitric oxide (NO) levels in Behçet's disease (BD) patients have been implicated in the development of the endothelial abnormalities and thrombotic complications occurring in these patients. This study investigated the association of the endothelial NO Synthase (eNOS) gene polymorphisms with BD.

METHODS

A case-control study was carried out using 193 unrelated Turkish BD patients and 106 healthy controls. All individuals were genotyped by PCR for two single-nucleotide polymorphisms (SNPs): -786 T-->C in the promoter region and 894 G-->T in exon 7 (Glu298Asp). A variable number of tandem repeats (VNTR) polymorphism in intron 4 was also investigated.

RESULTS

The VNTR polymorphism was associated with BD, detected by an increased frequency of the b allele (odds ratio = 1.9, P = 0.0069) and b/b genotype (odds ratio = 2.2, P = 0.002) in patients. After the stratification of cases according to the family history, a significant difference between familial cases and controls in the -786 SNP was observed, with an increase in the frequency of the T allele (odds ratio = 2.5, P = 0.0016) and T/T genotype (odds ratio = 2.5, P = 0.0085), and the association of the VNTR polymorphism with BD became stronger. The -786*T and VNTR*b alleles were in linkage disequilibrium (D' = 0.65, P <0.0001), and the number of individuals homozygous for the -786*T/VNTR*b haplotype was significantly increased in the patients.

CONCLUSIONS

eNOS gene polymorphisms are associated with BD, which might contribute to the reduced NO activity observed in BD patients.