PREVALENCE OF CELIAC DISEASE PREDISPOSING GENOTYPES, INCLUDING HLA-DQ2.2 VARIANT, IN BRAZILIAN CHILDREN

Role of HLA-DQB1 alleles in the risk, signs and symptoms, and severity of celiac disease in a Venezuelan population

INTRODUCTION AND AIMS

Celiac disease (CD) is a complex condition, whose main genetic determinant involves HLA molecules, specifically the HLA-DQ2 and/or HLA-DQ8 heterodimers. Nevertheless, the frequency of the alleles encoding those molecules has not been reported in Venezuelan celiac patients. Therefore, the aim of our study was to evaluate the frequency of the HLA-DQB1 alleles in individuals with symptoms suggestive of CD and define the diagnostic markers of the condition in a Venezuelan population.

MATERIAL AND METHODS

A cross-sectional study included 516 individuals with symptoms suggestive of CD. Molecular typing of the HLA-DQB1 locus was performed using a polymerase chain reaction-sequence-specific oligonucleotide procedure (PCR-SSO).

RESULTS

A total of 58.3% of the individuals with clinical manifestations consistent with CD presented with at least one risk allele (DQB1*0201 and/or DQB1*0302), and the diagnosis was confirmed in 40 of them. The patients with CD had a higher frequency of the DQB1*0201 risk allele (26.25%), followed by the DQB1*0302 (17.5%) allele. There was an association between the presence of risk alleles and the presence of lesions characteristic of CD (P = 0.001), and a correlation was found between the genetic predisposition to develop CD and the presence of anti-tissue transglutaminase antibodies (P = 0.0127).

CONCLUSIONS

The results support the role of the DQB1*02 and DQB1*0302 alleles in CD susceptibility and the histologic alterations of the intestinal mucosa, in a Venezuelan population.

Exome-Wide Search for Genes Associated With Central Nervous System Inflammatory Demyelinating Diseases Following CHIKV Infection: The Tip of the Iceberg

Chikungunya virus (CHIKV) is a re-emergent arbovirus that causes a disease characterized primarily by fever, rash and severe persistent polyarthralgia, although <1% of cases develop severe neurological manifestations such as inflammatory demyelinating diseases (IDD) of the central nervous system (CNS) like acute disseminated encephalomyelitis (ADEM) and extensive transverse myelitis. Genetic factors associated with host response and disease severity are still poorly understood. In this study, we performed whole-exome sequencing (WES) to identify HLA alleles, genes and cellular pathways associated with CNS IDD clinical phenotype outcomes following CHIKV infection. The cohort includes 345 patients of which 160 were confirmed for CHIKV. Six cases presented neurological manifestation mimetizing CNS IDD. WES data analysis was performed for 12 patients, including the CNS IDD cases and 6 CHIKV patients without any neurological manifestation. We identified 29 candidate genes harboring rare, pathogenic, or probably pathogenic variants in all exomes analyzed. HLA alleles were also determined and patients who developed CNS IDD shared a common signature with diseases such as Multiple sclerosis (MS) and Neuromyelitis Optica Spectrum Disorders (NMOSD). When these genes were included in Gene Ontology analyses, pathways associated with CNS IDD syndromes were retrieved, suggesting that CHIKV-induced CNS outcomesmay share a genetic background with other neurological disorders. To our knowledge, this study was the first genome-wide investigation of genetic risk factors for CNS phenotypes in CHIKV infection. Our data suggest that HLA-DRB1 alleles associated with demyelinating diseases may also confer risk of CNS IDD outcomes in patients with CHIKV infection.

Distribution of HLA-DQ risk genotypes for celiac disease in Ethiopian children

Most patients with celiac disease are positive for either HLA‐DQA1*05:01‐DQB1*02 (DQ2.5) or DQA1*03:01‐DQB1*03:02 (DQ8). Remaining few patients are usually DQA1*02:01‐DQB1*02 (DQ2.2) carriers. Screenings of populations with high frequencies of these HLA‐DQA1‐DQB1 haplotypes report a 1% to 3% celiac disease prevalence. The aim was to determine the prevalence of HLA‐DQ risk haplotypes for celiac disease in Ethiopian children. Dried blood spots collected from 1193 children from the Oromia regional state of Ethiopia were genotyped for HLA‐DQA1 and DQB1 genotyping using an asymmetric polymerase chain reaction (PCR) and a subsequent hybridization of allele‐specific probes. As references, 2000 previously HLA‐genotyped children randomly selected from the general population in Sweden were included. DQ2.2 was the most common haplotype and found in 15.3% of Ethiopian children, which was higher compared with 6.7% of Swedish references (P < .0001). Opposed to this finding, DQ2.5 and DQ8 occurred in 9.7% and 6.8% of Ethiopian children, which were less frequent compared with 12.8% and 13.1% of Swedish references, respectively (P < .0001). The DQ2.5‐trans genotype encoded by DQA1*05‐DQB1*03:01 in combination with DQ2.2 occurred in 3.6% of Ethiopian children, which was higher compared with 1.3% of Swedish references (P < .0001). However, when children with moderate high to very high‐risk HLA genotypes were grouped together, there was no difference between Ethiopian children and Swedish references (27.4% vs 29.0%) (P = .3504). The frequency of HLA risk haplotypes for celiac disease is very similar in Ethiopian and Swedish children. This finding of importance will be useful in future screening of children for celiac disease in Ethiopia.

HLA Haplotype Association with Celiac Disease in Albanian Pediatric Patients from Kosovo

Genetic predisposition to celiac disease (CD) is strongly associated with the presence of HLA alleles in the individual genotype encoding HLA-DQ2 and/or HLA-DQ8 heterodimers. The main aim of this study was to analyze the HLA-A, -B, -DRB1, and -DQ allele and five-locus haplotype frequencies in 60 Albanian pediatric CD patients and 124 non-CD children from Kosovo. The most prevalent haplotype in patients was the ancestral AH 8.1 haplotype present in 22.5% of the cases compared to 2.8% of the controls (P < 0.0001). Additionally, two other haplotypes were also overrepresented in patients (HLA-A^∗02~B^∗50~DRB1^∗07~DQA1^∗02:01~DQB1^∗02:02 and HLA-A^∗68~B^∗44~DRB1^∗07~DQA1^∗02:01~DQB1^∗02:02). Analysis showed that 95.0% of CD patients and 43.3% of controls were carriers of HLA-DQ2 and/or HLA-DQ8 heterodimers. The most frequent CD-predisposing HLA-DQ haplotypes in patients were HLA-DQ2.5 (46.7%) and HLA-DQ2.2 (11.6%), while the most prevalent genotypes were HLA-DQ2.5/DQX (58.3%) and HLA-DQ2.5/DQ2.2 (20.0%). The frequency of the HLA-DQ8 heterodimer among CD patients (4.2%) compared to the control group (8.1%) was without statistical significance. The given data demonstrate differences in the distribution of HLA haplotypes among Albanian CD patients from Kosovo in comparison to other European and non-European populations, as well as provide additional population data to supplement the thus far undisputed importance of the role of HLA-DQ2 and HLA-DQ8 heterodimers in the development of CD.

Frequency of HLA celiac disease risk alleles and haplotypes in healthy adults in Tamil Nadu

Celiac disease (CeD) occurs only in individuals who are able to express human leukocyte antigens (HLA) DQ2 or DQ8, and these are expressed in nearly a third of healthy people in the West. As the disease is very uncommon in Tamil Nadu, we evaluated the possibility that the relevant genes are infrequent in this population. Four hundred healthy adults without any gastrointestinal abnormalities were recruited from Vellore district of Tamil Nadu. Genomic DNA was extracted from venous blood and amplified by PCR using the allele-specific primers for the following alleles-DQA1*0201, 0301, and 0501 and DQB1*02, 0201, and 0302, which determine the CeD risk haplotypes. Among the 400 healthy adults, the presence of DQ2.5 (DQB1*0201-DQA1*0501) and DQ2.2 (DQB1*02-DQA1*0201) haplotypes was found in 8.25% and 14.25%, respectively. DQ8 (DQB1*0302-DQA1*0301) haplotype was identified in only 3% of healthy individuals. Overall, approximately a quarter of healthy adults in Tamil Nadu had the potential CeD risk haplotypes of HLA DQ2.5, DQ2.2, and DQ8.

A comprehensive review on the utility of capsule endoscopy in coeliac disease: From computational analysis to the bedside

Small bowel capsule endoscopy (SBCE) can identify macroscopic changes of coeliac disease and assess the extent of disease in the small bowel beyond the duodenum. SBCE has a good sensitivity for the detection of coeliac disease in comparison to histology owing to several ideal features such as a high magnification. It also plays a useful role in detecting complications in patients with refractory coeliac disease. Several studies have been carried out on transforming images obtained from small bowel capsule endoscopy to enable the automated detection of features related to coeliac disease. This review discusses the current roles played by small bowel capsule endoscopy in coeliac disease. It identifies future potential roles of this technique and describes in great detail the role of computational analysis in the detection of coeliac disease and how it can be adapted to current available technology.

Next-Generation Sequencing Based HLA Typing: Deciphering Immunogenetic Aspects of Sarcoidosis

Unraveling of the HLA-related immunogenetic basis of several immune disorders is complex due to the extensive HLA polymorphism and strong linkage-disequilibrium between HLA loci. A lack of in phase sequence information, a relative deficiency of high resolution genotyping including non-coding regions and ambiguous haplotype assignment make it difficult to compare findings across association studies and to attribute a causal role to specific HLA alleles/haplotypes in disease susceptibility and modification of disease phenotypes. Earlier, historical antibody and DNA-based methods of HLA typing, primarily of low resolution at antigen/alellic group levels, yielded "indicative" findings which were partially improved by high-resolution DNA-based typing. Only recently, next-generation sequencing (NGS) approaches based on deep-sequencing of the complete HLA genes combined with bioinformatics tools began to provide the access to complete information at an allelic level. Analyzing HLA with NGS approaches, therefore, promises to provide further insight in the etiopathogenesis of several immune disorders in which HLA associations have been implicated. These range from coeliac disease and rheumatological conditions to even more complex disorders, such as type-1 diabetes, systemic lupus erythematosus and sarcoidosis. A systemic disease of unknown etiology, sarcoidosis has previously been associated with numerous HLA variants and also other gene polymorphisms, often in linkage with the HLA region. To date, the biological significance of these associations has only partially been defined. Therefore, more precise assignments of HLA alleles/haplotypes using NGS approaches could help to elucidate the exact role of HLA variation in the multifaceted etiopathogenesis of sarcoidosis, including epigenetic mechanisms. NGS-based HLA analyses may be also relevant for defining variable clinical phenotypes and for predicting the disease course or the response to current/plausible novel therapies.

Frequency of HLA-DQ, susceptibility genotypes for celiac disease, in Brazilian newborns

Background

The frequency of HLA‐DQ2 and DQ8 predisposing genotypes for celiac disease (CD) has shown significant variation among different world regions and has not been previously determined among the highly interbred Brazilian population. The aim of this study was to investigate the frequency of these genotypes among Brazilian newborns (NB).

Methods

We typed DQA1*05 ‐ DQB1*02 (DQ2.5) and DQA1*03 ‐ DQB1*03:02 (DQ8) alleles in 329 NB using qPCR technique. Subsequently we confirmed our results by PCR‐SSP using a reference kit which further identified DQ2.2 (DQA1*02:01 ‐ DQB1*02).

Results

Among the 329 NB, using qPCR technique: 5 (1.52%) carried both DQ2.5 and DQ8 variants; 58 (17.63%) carried only DQ2.5 (DQA1*05 and DQB1*02) and 47 (14.29%) carried only the DQ8 (DQA1*03 and DQB1*03:02) variant. The use of the PCR‐SSP method yielded further information; among the 329 samples: 34 (10.34%) tested positive for DQ2.2 and among the 47 previously DQ8 positives samples, we found 10 (3.04%) that also tested positives for DQ2.2.

Conclusion

43.7% of the analyzed individual tested positive for at least one of the CD predisposing HLA‐DQ genotypes in our group of Brazilian NB. The highest frequency was found for DQ2.5 positive subjects (17.6%) followed by DQ8 (11.3%); DQ2.2 (10.3%); DQ8 and DQ2.2 (3.0%); DQ2.5 and DQ8 (1.5%). We found no positive sample for DQ2.5 associated with DQ2.2.