Non-invasive prenatal testing of beta-hemoglobinopathies using next generation sequencing, in-silico sequence size selection, and haplotyping.

AIM: To develop a non-invasive prenatal test for beta-hemoglobinopathies based on analyzing maternal plasma by using next generation sequencing. METHODS: We applied next generation sequencing (NGS) of maternal plasma to the non-invasive prenatal testing (NIPT) of autosomal recessive diseases, sickle cell disease and beta-thalassemia. Using the Illumina MiSeq, we sequenced plasma libraries obtained via a Twist Bioscience probe capture panel covering 4 Kb of chromosome 11, including the beta-globin (HBB) gene and >450 genomic single-nucleotide polymorphisms (SNPs) used to estimate the fetal fraction (FF). The FF is estimated by counting paternally transmitted allelic sequence reads present in the plasma but absent in the mother. We inferred fetal beta-globin genotypes by comparing the observed mutation (Mut) and reference (Ref) read ratios to those expected for the three possible fetal genotypes (Mut/Mut; Mut/Ref; Ref/Ref), based on the FF. RESULTS: We bioinformatically enriched the FF by excluding reads over a specified length via in-silico size selection (ISS), favoring the shorter fetal reads, which increased fetal genotype prediction accuracy. Finally, we determined the parental HBB haplotypes, which allowed us to use the read ratios observed at linked SNPs to help predict the fetal genotype at the mutation site(s). We determined HBB haplotypes via Oxford Nanopore MinION sequencing of a 2.2 kb amplicon and aligned these sequences using Soft Genetics' NextGENe LR software. CONCLUSION: The combined use of ISS and HBB haplotypes enabled us to correctly predict fetal genotypes in cases where the prediction based on variant read ratios alone was incorrect.

HLA-C dysregulation as a possible mechanism of immune evasion in SARS-CoV-2 and other RNA-virus infections.

One of the mechanisms by which viruses can evade the host's immune system is to modify the host's DNA methylation pattern. This work aims to investigate the DNA methylation and gene expression profile of COVID-19 patients, divided into symptomatic and asymptomatic, and healthy controls, focusing on genes involved in the immune response. In this study, changes in the methylome of COVID-19 patients' upper airways cells, the first barrier against respiratory infections and the first cells presenting viral antigens, are shown for the first time. Our results showed alterations in the methylation pattern of genes encoding proteins implicated in the response against pathogens, in particular the HLA-C gene, also important for the T-cell mediated memory response. HLA-C expression significantly decreases in COVID-19 patients, especially in those with a more severe prognosis and without other possibly confounding co-morbidities. Moreover, our bionformatic analysis revealed that the identified methylation alteration overlaps with enhancers regulating HLA-C expression, suggesting an additional mechanism exploited by SARS-CoV-2 to inhibit this fundamental player in the host's immune response. HLA-C could therefore represent both a prognostic marker and an excellent therapeutic target, also suggesting a preventive intervention that conjugate a virus-specific antigenic stimulation with an adjuvant increasing the T-cell mediated memory response.

Interaction between maternal killer immunoglobulin-like receptors and offspring HLAs and susceptibility of childhood ALL.

Acute lymphoblastic leukemia (ALL) in children is associated with a distinct neonatal cytokine profile. The basis of this neonatal immune phenotype is unknown but potentially related to maternal-fetal immune receptor interactions. We conducted a case-control study of 226 case child-mother pairs and 404 control child-mother pairs to evaluate the role of interaction between HLA genotypes in the offspring and maternal killer immunoglobulin-like receptor (KIR) genotypes in the etiology of childhood ALL, while considering potential mediation by neonatal cytokines and the immune-modulating enzyme arginase-II (ARG-II). We observed different associations between offspring HLA-maternal KIR activating profiles and the risk of ALL in different predicted genetic ancestry groups. For instance, in Latino subjects who experience the highest risk of childhood leukemia, activating profiles were significantly associated with a lower risk of childhood ALL (odds ratio [OR] = 0.59; 95% confidence interval [CI], 0.49-0.71) and a higher level of ARG-II at birth (coefficient = 0.13; 95% CI, 0.04-0.22). HLA-KIR activating profiles were also associated with a lower risk of ALL in non-Latino Asians (OR = 0.63; 95% CI, 0.38-1.01), although they had a lower tumor necrosis factor-α level (coefficient = -0.27; 95% CI, -0.49 to -0.06). Among non-Latino White subjects, no significant association was observed between offspring HLA-maternal KIR interaction and ALL risk or cytokine levels. The current study reports the association between offspring HLA-maternal KIR interaction and the development of childhood ALL with variation by predicted genetic ancestry. We also observed some associations between activating profiles and immune factors related to cytokine control; however, cytokines did not demonstrate causal mediation of the activating profiles on ALL risk.

Noninvasive Prenatal Test for ß-Thalassemia and Sickle Cell Disease Using Probe Capture Enrichment and Next-Generation Sequencing of DNA in Maternal Plasma.

BACKGROUND: Noninvasive prenatal testing (NIPT) of chromosomal aneuploidies based on next-generation sequencing (NGS) analysis of fetal DNA in maternal plasma is well established, but testing for autosomal recessive disorders remains challenging. NGS libraries prepared by probe capture facilitate the analysis of the short DNA fragments plasma. This system has been applied to the ß-hemoglobinopathies to reduce the risk to the fetus. METHOD: Our probe panel captures >4 kb of the HBB region and 435 single-nucleotide polymorphisms (SNPs) used to estimate fetal fraction. Contrived mixtures of DNA samples, plasma, and whole blood samples from 7 pregnant women with ß-thalassemia or sickle cell anemia mutations and samples from the father, sibling, and baby or chorionic villus were analyzed. The fetal genotypes, including point mutations and deletions, were inferred by comparing the observed and expected plasma sequence read ratios, based on fetal fraction, at the mutation site and linked SNPs. Accuracy was increased by removing PCR duplicates and by in silico size selection of plasma sequence reads. A probability was assigned to each of the potential fetal genotypes using a statistical model for the experimental variation, and thresholds were established for assigning clinical status. RESULTS: Using in silico size selection of plasma sequence files, the predicted clinical fetal genotype assignments were correct in 9 of 10 plasma libraries with maternal point mutations, with 1 inconclusive result. For 2 additional plasmas with deletions, the most probable fetal genotype was correct. The ß-globin haplotype determined from linked SNPs, when available, was used to infer the fetal genotype at the mutation site. CONCLUSION: This probe capture NGS assay demonstrates the potential of NIPT for ß-hemoglobinopathies.

Resolution of mitochondrial DNA mixtures using a probe capture next generation sequencing system and phylogenetic-based software.

Interpreting mixtures with nuclear genetic markers remains one of the persisting challenges in forensic DNA analysis, particularly when the DNA is degraded or present in trace amounts. In these scenarios, analyzing mitochondrial (mt) DNA can be useful due to the higher copy number per cell compared to nuclear DNA. However, until the emergence of Next-Generation Sequencing (NGS) with its clonal sequencing capability, analysis of mtDNA mixtures was very challenging. A mitochondrial genome probe capture Next-Generation Sequencing (NGS) system was used to sequence complex mtDNA mixtures and two different software programs to analyze the sequence data. Analysis of contrived mixtures of two contributors in 50:50 and 95:5 ratios as well as three-person mixtures ranging from near equal proportions (~33:33:33 ratio) to low amounts of the minor contributors (e.g., a 90:5:5 ratio) is reported. This system was also applied to the analysis of mtDNA mixtures from forensically relevant samples. For data analysis, both the variant frequency-based software program GeneMarker®HTS and the phylogenetic-based software program Mixemt was used to de-convolute the mixtures. Using the massively parallel, clonal features of NGS, one can bioinformatically separate and count the individual sequence reads to calculate the proportions of individual contributors using phylogenetically informative polymorphisms. GeneMarker®HTS allows us to detect all mutations, including "private" mutations (non-phylogenetically informative polymorphisms) and assign them to individual contributors based on the frequency of the sequence reads, provided that the proportions of the various contributors are sufficiently different. Using a probe capture NGS system and both GeneMarker®HTS and Mixemt software programs, the interpretation of complex mixtures of equal proportion contributors, trace amount contributors, and more than two contributors in contrived mixtures, as well as interpretation of challenging forensic specimens is demonstrated.

Type 1 Diabetes Risk in African-Ancestry Participants and Utility of an Ancestry-Specific Genetic Risk Score.

OBJECTIVE: Genetic risk scores (GRS) have been developed that differentiate individuals with type 1 diabetes from those with other forms of diabetes and are starting to be used for population screening; however, most studies were conducted in European-ancestry populations. This study identifies novel genetic variants associated with type 1 diabetes risk in African-ancestry participants and develops an African-specific GRS. RESEARCH DESIGN AND METHODS: We generated single nucleotide polymorphism (SNP) data with the ImmunoChip on 1,021 African-ancestry participants with type 1 diabetes and 2,928 control participants. HLA class I and class II alleles were imputed using SNP2HLA. Logistic regression models were used to identify genome-wide significant (P < 5.0 × 10-8) SNPs associated with type 1 diabetes in the African-ancestry samples and validate SNPs associated with risk in known European-ancestry loci (P < 2.79 × 10-5). RESULTS: African-specific (HLA-DQA1*03:01-HLA-DQB1*02:01) and known European-ancestry HLA haplotypes (HLA-DRB1*03:01-HLA-DQA1*05:01-HLA-DQB1*02:01, HLA-DRB1*04:01-HLA-DQA1*03:01-HLA-DQB1*03:02) were significantly associated with type 1 diabetes risk. Among European-ancestry defined non-HLA risk loci, six risk loci were significantly associated with type 1 diabetes in subjects of African ancestry. An African-specific GRS provided strong prediction of type 1 diabetes risk (area under the curve 0.871), performing significantly better than a European-based GRS and two polygenic risk scores in independent discovery and validation cohorts. CONCLUSIONS: Genetic risk of type 1 diabetes includes ancestry-specific, disease-associated variants. The GRS developed here provides improved prediction of type 1 diabetes in African-ancestry subjects and a means to identify groups of individuals who would benefit from immune monitoring for early detection of islet autoimmunity.

High resolution HLA analysis reveals independent class I haplotypes and amino-acid motifs protective for multiple sclerosis.

We investigated association between HLA class I and class II alleles and haplotypes, and KIR loci and their HLA class I ligands, with multiple sclerosis (MS) in 412 European American MS patients and 419 ethnically matched controls, using next-generation sequencing. The DRB1*15:01~DQB1*06:02 haplotype was highly predisposing (odds ratio (OR) = 3.98; 95% confidence interval (CI) = 3-5.31; p-value (p) = 2.22E-16), as was DRB1*03:01~DQB1*02:01 (OR = 1.63; CI = 1.19-2.24; p = 1.41E-03). Hardy-Weinberg (HW) analysis in MS patients revealed a significant DRB1*03:01~DQB1*02:01 homozyote excess (15 observed; 8.6 expected; p = 0.016). The OR for this genotype (5.27; CI = 1.47-28.52; p = 0.0036) suggests a recessive MS risk model. Controls displayed no HW deviations. The C*03:04~B*40:01 haplotype (OR = 0.27; CI = 0.14-0.51; p = 6.76E-06) was highly protective for MS, especially in haplotypes with A*02:01 (OR = 0.15; CI = 0.04-0.45; p = 6.51E-05). By itself, A*02:01 is moderately protective, (OR = 0.69; CI = 0.54-0.87; p = 1.46E-03), and haplotypes of A*02:01 with the HLA-B Thr80 Bw4 variant (Bw4T) more so (OR = 0.53; CI = 0.35-0.78; p = 7.55E-04). Protective associations with the Bw4 KIR ligand resulted from linkage disequilibrium (LD) with DRB1*15:01, but the Bw4T variant was protective (OR = 0.64; CI = 0.49-0.82; p = 3.37-04) independent of LD with DRB1*15:01. The Bw4I variant was not associated with MS. Overall, we find specific class I HLA polymorphisms to be protective for MS, independent of the strong predisposition conferred by DRB1*15:01.

Correction: High resolution HLA analysis reveals independent class I haplotypes and amino-acid motifs protective for multiple sclerosis.

Since the publication of this article, the authors have found that the numbers of patients and controls were reversed. This study included 412 MS patients and 419 controls. This correction applies to the Abstract, the final paragraph of the Introduction, and the first paragraph of the Materials and Methods. This was entirely a reporting error and does not impact the Results or Conclusions.

Target capture enrichment of nuclear SNP markers for massively parallel sequencing of degraded and mixed samples.

DNA from biological forensic samples can be highly fragmented and present in limited quantity. When DNA is highly fragmented, conventional PCR based Short Tandem Repeat (STR) analysis may fail as primer binding sites may not be present on a single template molecule. Single Nucleotide Polymorphisms (SNPs) can serve as an alternative type of genetic marker for analysis of degraded samples because the targeted variation is a single base. However, conventional PCR based SNP analysis methods still require intact primer binding sites for target amplification. Recently, probe capture methods for targeted enrichment have shown success in recovering degraded DNA as well as DNA from ancient bone samples using next-generation sequencing (NGS) technologies. The goal of this study was to design and test a probe capture assay targeting forensically relevant nuclear SNP markers for clonal and massively parallel sequencing (MPS) of degraded and limited DNA samples as well as mixtures. A set of 411 polymorphic markers totaling 451 nuclear SNPs (375 SNPs and 36 microhaplotype markers) was selected for the custom probe capture panel. The SNP markers were selected for a broad range of forensic applications including human individual identification, kinship, and lineage analysis as well as for mixture analysis. Performance of the custom SNP probe capture NGS assay was characterized by analyzing read depth and heterozygote allele balance across 15 samples at 25 ng input DNA. Performance thresholds were established based on read depth ≥500X and heterozygote allele balance within ±10% deviation from 50:50, which was observed for 426 out of 451 SNPs. These 426 SNPs were analyzed in size selected samples (at ≤75 bp, ≤100 bp, ≤150 bp, ≤200 bp, and ≤250 bp) as well as mock degraded samples fragmented to an average of 150 bp. Samples selected for ≤75 bp exhibited 99-100% reportable SNPs across varied DNA amounts and as low as 0.5 ng. Mock degraded samples at 1 ng and 10 ng exhibited >90% reportable SNPs. Finally, two-person male-male mixtures were tested at 10 ng in contributor varying ratios. Overall, 85-100% of alleles unique to the minor contributor were observed at all mixture ratios. Results from these studies using the SNP probe capture NGS system demonstrates proof of concept for application to forensically relevant degraded and mixed DNA samples.

Correction: Shelly Y. Shih; et al.; Applications of Probe Capture Enrichment Next Generation Sequencing for Whole Mitochondrial Genome and 426 Nuclear SNPs for Forensically Challenging Samples. Genes 2018, 9, 49.

The authors wish to make the following change to their paper [1][...].

Applications of Probe Capture Enrichment Next Generation Sequencing for Whole Mitochondrial Genome and 426 Nuclear SNPs for Forensically Challenging Samples.

The application of next generation sequencing (NGS) for the analysis of mitochondrial (mt) DNA, short tandem repeats (STRs), and single nucleotide polymorphism (SNPs) has demonstrated great promise for challenging forensic specimens, such as degraded, limited, and mixed samples. Target enrichment using probe capture rather than PCR amplification offers advantages for analysis of degraded DNA since two intact PCR primer sites in the template DNA molecule are not required. Furthermore, NGS software programs can help remove PCR duplicates to determine initial template copy numbers of a shotgun library. Moreover, the same shotgun library prepared from a limited DNA source can be enriched for mtDNA as well as nuclear markers by hybrid capture with the relevant probe panels. Here, we demonstrate the use of this strategy in the analysis of limited and mock degraded samples using our custom probe capture panels for massively parallel sequencing of the whole mtgenome and 426 SNP markers. We also applied the mtgenome capture panel in a mixed sample and analyzed using both phylogenetic and variant frequency based bioinformatics tools to resolve the minor and major contributors. Finally, the results obtained on individual telogen hairs demonstrate the potential of probe capture NGS analysis for both mtDNA and nuclear SNPs for challenging forensic specimens.

Co-occurrence of Type 1 Diabetes and Celiac Disease Autoimmunity.

BACKGROUND AND OBJECTIVES: Few birth cohorts have prospectively followed development of type 1 diabetes (T1D) and celiac disease (CD) autoimmunities to determine timing, extent of co-occurrence, and associated genetic and demographic factors. METHODS: In this prospective birth cohort study, 8676 children at high genetic risk of both diseases were enrolled and 5891 analyzed in median follow-up of 66 months. Along with demographic factors and HLA-DR-DQ, genotypes for HLA-DPB1 and 5 non-HLA loci conferring risk of both T1D and CD were analyzed. RESULTS: Development of persistent islet autoantibodies (IAs) and tissue transglutaminase autoantibodies (tTGAs), as well as each clinical disease, was evaluated quarterly from 3 to 48 months of age and semiannually thereafter. IAs alone appeared in 367, tTGAs alone in 808, and both in 90 children. Co-occurrence significantly exceeded the expected rate. IAs usually, but not always, appeared earlier than tTGAs. IAs preceding tTGAs was associated with increasing risk of tTGAs (hazard ratio [HR]: 1.48; 95% confidence interval [CI]: 1.15-1.91). After adjusting for country, sex, family history, and all other genetic loci, significantly greater co-occurrence was observed in children with a T1D family history (HR: 2.80), HLA-DR3/4 (HR: 1.94) and single-nucleotide polymorphism rs3184504 at SH2B3 (HR: 1.53). However, observed co-occurrence was not fully accounted for by all analyzed factors. CONCLUSIONS: In early childhood, T1D autoimmunity usually precedes CD autoimmunity. Preceding IAs significantly increases the risk of subsequent tTGAs. Co-occurrence is greater than explained by demographic factors and extensive genetic risk loci, indicating that shared environmental or pathophysiological mechanisms may contribute to the increased risk.

A phylogenetic approach for haplotype analysis of sequence data from complex mitochondrial mixtures.

Massively parallel (next-generation) sequencing provides a powerful method to analyze DNA from many different sources, including degraded and trace samples. A common challenge, however, is that many forensic samples are often known or suspected mixtures of DNA from multiple individuals. Haploid lineage markers, such as mitochondrial (mt) DNA, are useful for analysis of mixtures because, unlike nuclear genetic markers, each individual contributes a single sequence to the mixture. Deconvolution of these mixtures into the constituent mitochondrial haplotypes is challenging as typical sequence read lengths are too short to reconstruct the distinct haplotypes completely. We present a powerful computational approach for determining the constituent haplotypes in massively parallel sequencing data from potentially mixed samples. At the heart of our approach is an expectation maximization based algorithm that co-estimates the overall mixture proportions and the source haplogroup for each read individually. This approach, implemented in the software package mixemt, correctly identifies haplogroups from mixed samples across a range of mixture proportions. Furthermore, our method can separate fragments in a mixed sample by the most likely originating contributor and generate reconstructions of the constituent haplotypes based on known patterns of mtDNA diversity.

MHC class II super-enhancer increases surface expression of HLA-DR and HLA-DQ and affects cytokine production in autoimmune vitiligo.

Genetic risk for autoimmunity in HLA genes is most often attributed to structural specificity resulting in presentation of self-antigens. Autoimmune vitiligo is strongly associated with the MHC class II region. Here, we fine-map vitiligo MHC class II genetic risk to three SNPs only 47 bp apart, located within a predicted super-enhancer in an intergenic region between HLA-DRB1 and HLA-DQA1, localized by a genome-wide association study of 2,853 Caucasian vitiligo patients. The super-enhancer corresponds to an expression quantitative trait locus for expression of HLA-DR and HLA-DQ RNA; we observed elevated surface expression of HLA-DR (P = 0.008) and HLA-DQ (P = 0.02) on monocytes from healthy subjects homozygous for the high-risk SNP haplotype. Unexpectedly, pathogen-stimulated peripheral blood mononuclear cells from subjects homozygous for the high-risk super-enhancer haplotype exhibited greater increase in production of IFN-γ and IL-1ß than cells from subjects homozygous for the low-risk haplotype. Specifically, production of IFN-γ on stimulation of dectin-1, mannose, and Toll-like receptors with Candida albicans and Staphylococcus epidermidis was 2.5- and 2.9-fold higher in high-risk subjects than in low-risk subjects, respectively (P = 0.007 and P = 0.01). Similarly, production of IL-1ß was fivefold higher in high-risk subjects than in low-risk subjects (P = 0.02). Increased production of immunostimulatory cytokines in subjects carrying the high-risk haplotype may act as an "adjuvant" during the presentation of autoantigens, tying together genetic variation in the MHC with the development of autoimmunity. This study demonstrates that for risk of autoimmune vitiligo, expression level of HLA class II molecules is as or more important than antigen specificity.

The Role of Human Papillomavirus Genotyping in Cervical Cancer Screening: A Large-Scale Evaluation of the cobas HPV Test.

BACKGROUND: The cobas HPV Test ("cobas"; Roche Molecular Systems) detects HPV16 and HPV18 individually, and a pool of 12 other high-risk (HR) HPV types. The test is approved for (i) atypical squamous cells of undetermined significance (ASC-US) triage to determine need for colposcopy, (ii) combined screening with cytology ("cotesting"), and (iii) primary HPV screening. METHODS: To assess the possible value of HPV16/18 typing, >17,000 specimens from a longitudinal cohort study of initially HPV-positive women (HC2, Qiagen) were retested with cobas. To study accuracy, cobas genotyping results were compared with those of an established method, the Linear Array HPV Genotyping Test (LA, Roche Molecular Systems). Clinical value of the typing strategy was evaluated by linking the cobas results (supplemented by other available typing results) to 3-year cumulative risks of CIN3+. RESULTS: Grouped hierarchically (HPV16, else HPV18, else other HR types, else negative), the κ statistic for agreement between cobas and LA was 0.86 [95% confidence interval (CI), 0.86-0.87]. In all three scenarios, HPV16-positive women were at much higher 3-year risk of CIN3+ than HPV16-negative women: women ages 21 and older with ASC-US (14.5%; 95% CI, 13.5%-15.5% vs. 3.5%; 95% CI, 3.3-3.6); women ages 30 years and older that were HPV-positive cytology-negative (10.3%; 95% CI, 9.6-11.1 vs. 2.3%; 95% CI, 2.2-2.4); and all women 25 years and older that were HPV-positive (18.5%; 95% CI, 17.8-19.2 vs. 4.3%; 95% CI, 4.2-4.4). CONCLUSION: The cobas and LA results show excellent agreement. The data support HPV16 typing. IMPACT: HPV16 typing is useful in the management of HPV-positive/cytology-negative women in cotesting, of all HPV-positive women in primary HPV testing, and perhaps in the management of HPV-positive women with ASC-US. Cancer Epidemiol Biomarkers Prev; 24(9); 1304-10.

Analysis of mixtures using next generation sequencing of mitochondrial DNA hypervariable regions.

AIM: To apply massively parallel and clonal sequencing (next generation sequencing or NGS) to the analysis of forensic mixed samples. METHODS: A duplex polymerase chain reaction (PCR) assay targeting the mitochondrial DNA (mtDNA) hypervariable regions I/II (HVI/HVII) was developed for NGS analysis on the Roche 454 GS Junior instrument. Eight sets of multiplex identifier-tagged 454 fusion primers were used in a combinatorial approach for amplification and deep sequencing of up to 64 samples in parallel. RESULTS: This assay was shown to be highly sensitive for sequencing limited DNA amounts (~100 mtDNA copies) and analyzing contrived and biological mixtures with low level variants (~1%) as well as "complex" mixtures (≥3 contributors). PCR artifact "hybrid" sequences generated by jumping PCR or template switching were observed at a low level (<2%) in the analysis of mixed samples but could be eliminated by reducing the PCR cycle number. CONCLUSION: This study demonstrates the power of NGS technologies targeting the mtDNA HVI/HVII regions for analysis of challenging forensic samples, such as mixtures and specimens with limited DNA.

HLA-DPB1*04:01 Protects Genetically Susceptible Children from Celiac Disease Autoimmunity in the TEDDY Study.

OBJECTIVES: Tissue transglutaminase autoantibodies (tTGAs) represent the first evidence of celiac disease (CD) development. Associations of HLA-DR3-DQA1*05:01-DQB1*02:01 (i.e., DR3-DQ2) and, to a lesser extent, DR4-DQA1*03:01-DQB1*03:02 (i.e., DR4-DQ8) with the risk of CD differ by country, consistent with additional genetic heterogeneity that further refines risk. Therefore, we examined human leukocyte antigen (HLA) factors other than DR3-DQ2 for their contribution to developing tTGAs. METHODS: The Environmental Determinants of Diabetes in the Young (TEDDY) study enrolled 8,676 infants at an increased HLA-DR-DQ risk for type 1 diabetes and CD into a 15-year prospective surveillance follow-up. Of those followed up, 21% (n=1,813) carried DR3-DQ2/DR3-DQ2, 39% (n=3,359) carried DR3-DQ2/DR4-DQ8, 20% (n=1701) carried DR4-DQ8/DR4-DQ8, and 17% (n=1,493) carried DR4-DQ8/DQ4. Within TEDDY, a nested case-control design of 248 children with CD autoimmunity (CDA) and 248 matched control children were genotyped for HLA-B, -DRB3, -DRB4, -DPA1, and -DPB1 genes, and the entire cohort was genotyped for single-nucleotide polymorphisms (SNPs) using the Illumina ImmunoChip. CDA was defined as a positive tTGA test at two consecutive clinic visits, whereas matching in those with no evidence of tTGAs was based on the presence of HLA-DQ2, country, and sex. RESULTS: After adjustment for DR3-DQ2 and restriction to allele frequency (AF) ≥5%, HLA-DPB1*04:01 was inversely associated with CDA by conditional logistic regression (AF=44%, odds ratio=0.71, 95% confidence interval (CI)=0.53-0.96, P=0.025). This association of time to CDA and HLA-DPB1*04:01 was replicated with statistical significance in the remainder of the cohort using imputation for specific HLA alleles based on SNP genotyping (hazard ratio=0.84, 95% CI=0.73-0.96, P=0.013). CONCLUSIONS: HLA-DPB1*04:01 may reduce the risk of tTGAs, an early marker of CD, among DR3-DQ2 children, confirming that additional variants in the HLA region influence the risk for CDA.