Multiplex PCR typing of the three most frequent HLA alleles in celiac disease

A population-wide applicable HLA-DQ2 and DQ8 genotyping using DNA from dried blood spots and duplex allele-specific qPCR amplification

Genotyping of HLA-DQ2 and DQ8 haplotypes is important for diagnosis or for screening of early risk detection of celiac disease or type 1 diabetes. Usually, venous blood DNA extraction and expensive and time consuming amplification are used, that hinder population-wide studies. We assayed a friendly HLA-DQ2 and DQ8 genotyping procedure using a combination of DNA from dried blood spot (DBS) and duplex allele-specific qPCR amplification using SYBR Green. DNA was extracted using home-made buffers and compared to an extraction commercial kit. Duplex reactions by qPCR were designed using each Tm allele amplicon for reference samples (positive HLA-DQ2 or DQ8) with allele-specific primers. DBS samples from 558 children (7.99 ± 2.47 y) were collected. The DNA final yield obtained by the home-made extractive procedure was higher than from the commercial kit (1.11 ± 0.56 vs 0.23 ± 0.14 μg), while the quality was similar for both DNA samples. There was concordance in the amplification profiles for DNA samples obtained with both methods. All of four alleles from DQ2 and DQ8 haplotypes were accurately identified in duplex reactions. By using DBS samples and DNA extraction home-made procedure, the costs were reduced by 60%. The whole procedure is cost-effective for HLA-DQ2 and DQ8 genotyping.

HLA-DQ B1*0201 and A1*0102 Alleles Are Not Responsible for Antituberculosis Drug-Induced Hepatotoxicity Risk in Spanish Population

Aims

To evaluate the role of human leukocyte antigen (HLA) class II DQB1*0201 and DQA1*0102 in the risk of antituberculosis drug (ATD)-induced hepatotoxicity (ATDH) in a cohort of tuberculosis patients of Caucasian origin from Spain.

Methods

Matched case-control study including active tuberculosis (TB) patients from Spain (Caucasian) treated with first-line ATD (Isoniazid, Rifampin, and Pyrazinamide). Presence or absence of HLA class II DQB1*0201 and DQA1*0102 alleles were compared between cases and controls.

Results

We included 110 TB patients, 55 ATDH cases, and 55 sex-matched controls. The analysis of the presence of HLA-DQB1*0201 and HLA-DQA*0102 did not show significative differences between both groups [presence of HLA-DQB1*0201 53.6% of the cases vs. 45.4% of the controls, OR: 1.63 95% CI (0.62–4.52) p = 0.38; presence of HLA-DQA*0102 7.5% of cases vs. 20% of controls, OR: 0.36 95% CI (0.08–1.23) p = 0.12]. After multivariate logistic regression analysis including in the model, other potential risk factors of hepatotoxicity HLA class II DQB1*0201 and DQA1*0102 alleles were not found significantly associated with the risk of development ATDH. We could not demonstrate an association between HLA-DQA1*0102 and HLA-DQB1*0201 with the risk of ATDH in this Caucasian population of Spanish origin.

DQ2, DQ7 and DQ8 Distribution and Clinical Manifestations in Celiac Cases and Their First-Degree Relatives

HLA-linked genes are relevant to celiac disease (CD); the potential genetic differences present worldwide are not fully understood. Previous results suggest that the distribution of HLA-DQ2/DQ7/DQ8 in Chile may differ from that in Europe and North America. In celiac patients and their first-degree relatives (FDRS), we assessed their clinical, serological and histological characteristics, determined HLA-DQ2, HLA-DQ7 and HLA-DQ8 alleles and genotypes, and evaluated the relations between them. A total of 222 individuals were assessed (56 cases, 166 FDRs). 16.9% of FDRs were tTG positive; 53.6% of them showed overweight/obesity and 3% undernourishment; they spontaneously declared being asymptomatic, but detailed questioning revealed that 60.7% experienced symptoms, which had not been investigated. DQ2 was present in 53.9% and 43.9.0% of cases and FDRs (p < 0.05). The most frequent genotype distribution was DQ2/DQ7 (fr 0.392 (cases) and 0.248 (FDRs), respectively, p < 0.02). The next most common genotypes were HLA-DQ2/DQ8 (fr 0.236 in FDRs and 0.176 in cases, p < 0.05). 3.92% cases were not HLA-DQ2/DQ8 carriers. Among tTG positive FDRs, 57.4%, 22.3% and 20.2% carried DQ2, DQ7 and DQ8, respectively. In cases, 72.7% of the biopsies classified Marsh ≥ 3 carried at least one DQ2; 91.7% of DQ2/DQ2 and 88.3% of DQ2/DQ7 were Marsh ≥ 3. Thus, DQ2 frequency is lower than reported; the higher frequency found for DQ8 and DQ7 concur with recent publications from Argentine and Brazil. These results suggest that although CD may manifest clinically in ways similar to those described in other populations, some genetic peculiarities in this region deserve further study.

Serological screening for celiac disease in symptomatic 12 to 36 month-old children

CONTEXT

The correct diagnosis of celiac disease in environmentally deprived children is frequently hindered by the common presence of other causes for the classical celiac disease symptoms: malnutrition, failure to thrive and frequent diarrheas.

OBJECTIVES

To determine the prevalence of celiac disease in a group of 12 to 36 month-old children using immunoglobulin antibodies against gliadin (IgG and IgA-AGA), against endomysium (IgA-EMA), and against human tissue transglutaminase (IgA-tTG) as screening method.

METHODS

A total of 214 children (114 boys), aged 12 to 36 months, on gluten-containing diet, were admitted to the study. IgG and IgA-AGA, IgA-tTG and IgA-EMA tests were performed in all sera. Biopsy was obtained from all children showing positive result in one or more of the serologic tests, excluding those in which IgG-AGA had been the only positive result. In those cases, polymerase chain reaction (PCR) HLA genotyping for the identification of celiac disease predisposing alleles was applied. HLA genotyping was also performed to confirm the diagnosis in children identified as celiac by means of positive serologic testing and compatible biopsy results.

RESULTS

Normal results were obtained in 131 children. Ten children out of 68 identified as positive exclusively on the IgG-AGA test disclosed the presence of celiac disease predisposing alleles on PCR and underwent jejunal biopsy with normal results. All serologic tests were positive in four children. A fifth child showed positive IgG and IgA-AGA and IgA-tTG results but disclosed a negative IgA-EMA test. Jejunal biopsy of these five children revealed characteristic lesions of celiac disease.

CONCLUSION

A prevalence of 2.3% was found among symptomatic 12- to 36-month-old children that had not been previously diagnosed as celiac.

Italian paediatricians' approach to coeliac disease diagnosis

The aim of this study was to investigate the current implementation of the 1990 ESPGHAN criteria for the diagnosis of celiac disease (CD) in Italy to form a foundation for their revision. From September 2006 to March 2007 a nationwide questionnaire concerning current diagnostic methods was sent by mail to 54 Italian centres for the diagnosis of CD, which were distributed across the entire national territory. The questionnaire investigated the tests performed, diagnostic criteria currently used, and the management of some special cases in each centre. Eighty percent of the centres use anti-tissue transglutaminase to diagnose CD and anti-endomysium antibodies to confirm the results. Fifty-five percent still use anti-gliadin antibodies. A total of 87.5% of centres perform HLA typing, especially in first-degree relatives and in unclear diagnosis. Regarding histology, 67.5% of centres consider an infiltrative lesion consistent with diagnosis of CD. The majority of centres (85%) use the 1990 ESPGHAN criteria for both symptomatic and asymptomatic patients, but 80% do not perform a second biopsy in asymptomatic cases or a gluten challenge in children younger than 2 years of age. Furthermore, most centres (72.5%) do not prescribe a gluten-free diet to asymptomatic patients with positive serology and normal bowel architecture (ie, potential cases), but they do program a careful follow-up. In conclusion, ESPGHAN criteria are widely followed by Italian CD centres. However, their revision may be useful, but it should be evidence based. Large, multicentre studies are greatly needed.

Human leukocyte antigen DR4 is associated with inferior progression-free survival following allogeneic hematopoietic stem cell transplantation for lymphoid malignancies

The Class II human leukocyte antigen (HLA) DRB1 antigen DR4 is associated with autoimmune disorders and response to cyclosporine immunosuppression in T-lymphoproliferative disorders. We retrospectively reviewed the role of HLA DR4 on outcomes in 77 related and 22 unrelated consecutive first HLA-matched alloHSCT patients with lymphoid malignancies treated between 1992 and 2003. HLA DRB1 typing was determined by molecular (n = 69) or serologic (n = 30) methods. The proportion of patients with one HLA DR4 antigen was 18% (18/99). At a median follow-up of 5.6 years, there were no significant differences in aGvHD, cGvHD and OS between the HLA DR4 positive versus negative patients in any disease or donor subgroups. Nine of 18 (50%) DR4 positive patients and 20 of 81 (25%) DR4 negative patients had disease progression post HSCT (p = 0.033). Progression-free survival (PFS) at 3 years was 29% in the DR4 positive group and 70% in the DR4 negative group (p = 0.004). In univariate and multivariate analyses, DR4 positivity was the only significant factor associated with PFS (RR = 3.2, p = 0.007). Our results suggest that in addition to the known role of HLA DRB1 disparity in mediating histocompatibility, HLA DR4 is associated with inferior PFS in patients with lymphoid malignancy undergoing alloHSCT.

Increased prevalence of celiac disease without gastrointestinal symptoms in adults MICA 5.1 homozygous subjects from the Campania area

OBJECTIVES

Polymorphisms in the major histocompatibility complex class I chain-related gene A may influence its binding to the Natural Killer Cell Receptor G2D (NKG2D). We looked for polymorphisms in major histocompatibility complex class I chain-related gene A exon 5 and in Human Leukocyte Antigen (HLA)-DQ/DR in adult coeliac disease patients to determine whether they affected coeliac disease phenotypes.

METHODS

Adult coeliac disease patients with (n=98) and without (n=93) gastrointestinal symptoms (gastrointestinal symptoms+/gastrointestinal symptoms-) and 108 control subjects from Campania (Italy) were characterized by Polymerase Chain Reaction (PCR) sequence specific oligonucleotide followed by PCR sequence specific primer assays for HLA DQ/DR, and by PCR followed by capillary electrophoresis for major histocompatibility complex class I chain-related gene A exon 5 polymorphisms. Immunoglobulin A (IgA) anti-transglutaminase antibodies were also evaluated by immunosorbent assay.

RESULTS

Five different major histocompatibility complex class I chain-related gene A alleles were detected in both coeliac disease patients and control subjects. The major histocompatibility complex class I chain-related gene A 5.1 allele occurred more frequently in patients than in controls (p<0.05), and the major histocompatibility complex class I chain-related gene A 5.1/5.1 homozygous genotype increased the risk of gastrointestinal symptoms- coeliac disease (OR=2.79, 95% CI 1.15-6.79). Gastrointestinal symptoms- coeliac disease patients bearing major histocompatibility complex class I chain-related gene A 5.1/5.1 alleles showed lower anti-transglutaminase levels (18U/L) than the gastrointestinal symptoms+ coeliac disease patients (35U/L). HLA-DQ2/DQ8 genotypes did not differ between gastrointestinal symptoms+ and gastrointestinal symptoms- coeliac disease, although DQ8 tended to be more frequent in gastrointestinal symptoms- coeliac disease (11.7%) than in gastrointestinal symptoms+ coeliac disease (6%).

CONCLUSIONS

Our study shows that a double dose of the major histocompatibility complex class I chain-related gene A 5.1 allele could predispose to the onset of gastrointestinal symptoms- coeliac disease. We can hypothesize that a lower level of immunological involvement in gastrointestinal symptoms- coeliac disease patients is associated with absence of gastrointestinal symptoms. This test could represent a second step in the genetic typing of high-risk subjects such as first-degree relatives of coeliac disease patients positive for the DQ2/DQ8 molecule.

Use of HLA typing in diagnosing celiac disease in patients with type 1 diabetes

OBJECTIVE

This study examines the use of HLA typing for the diagnosis of celiac disease in a group of Australians with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Subjects included 131 sequential patients with type 1 diabetes (mean age 17 years [range 10-37]), 77 patients with biopsy-proven celiac disease (mean age 52 years [range 12-84]), and 162 healthy control subjects (mean age 17 years [range 2 months to 56 years]). Subjects were prospectively screened for celiac disease using endomysial antibodies (EMAs), tissue transglutaminase antibodies (TTGAs), and celiac disease-specific HLA typing.

RESULTS

Celiac disease was diagnosed in 11 subjects after an intestinal biopsy (prevalence 8.4%). There was 95% agreement between TTGA and EMA for positive results and 100% for negative results. There was no significant difference for HLA DQ2 and DR4 among patients with type 1 diabetes with or without celiac disease.

CONCLUSIONS

The prevalence of celiac disease among patients with type 1 diabetes is higher than previously estimated in Australia. TTGA is a valuable diagnostic tool that can be used for screening celiac disease in patients with type 1 diabetes. HLA typing should not be used in the diagnosis of celiac disease in patients with type 1 diabetes because of the similarities of HLA types between patients with type 1 diabetes and those with celiac disease.

New developments in celiac disease

Celiac disease remains a challenge to the clinician and scientist. It is clearly more prevalent than was previously suspected. Much interest is seen in identifying the genetic factors, which predispose to disease and the environmental agents that can trigger it. Genome-wide searches have identified a number of chromosomal susceptibility loci. Specific gliadin epitopes are being analyzed. New diagnostic options include the tissue transglutaminase enzyme-linked immunosorbent assay. Neurologic disease and bone disease are intriguing complications of celiac disease and are gradually being defined.