Cancer incidence in a cohort of Danish firefighters: An extended long-term follow-up 1968-2021.

OBJECTIVES: To update and extend the examination of cancer incidence in a cohort of Danish firefighters, now adding 7 years of follow-up and 2766 additional firefighters. The primary focus was directed toward cancer sites that recently contributed to the hazard evaluation conducted by the International Agency for Research on Cancer (IARC). METHODS: The updated cohort consisted of 11,827 male Danish firefighters who were followed up for cancer from 1968 to 2021. Cohort cancer morbidity was compared with a working population reference group, and standardized incidence ratios (SIR) were used for estimation of relative risks, along with 95% confidence intervals (95% CI). RESULTS: Among full-time firefighters, SIR of skin melanoma was 1.30 (95% CI: 1.02-1.66), and SIR = 1.37 (95% CI: 1.02-1.85) for over 5 years of employment. Slightly positive associations were also observed for cancer of the urinary bladder (SIR = 1.16; 95% CI: 0.93-1.45), prostate (SIR = 1.11; 95% CI: 0.97-1.28), and testis (SIR = 1.11; 95% CI: 0.75-1.63). CONCLUSIONS: This updated study provides evidence indicating an elevated risk of skin melanoma in firefighters. Consistent with IARC's evaluation, we also identified positive associations for urinary bladder, prostate, and testis cancer. In contrast, our findings did not suggest an increased risk of colon cancer, non-Hodgkin lymphoma, and mesothelioma. The latter may be due to small numbers in our still relatively young cohort. Continuous follow-up for cancer in firefighters is warranted, including assessment of influence from surveillance bias.

Online SPE-LC-MS-MS method for eight hydroxylated metabolites of polycyclic aromatic hydrocarbons in urine and determination of optimal sampling time after firefighter training.

Polycyclic aromatic compounds (PAHs) are formed during incomplete combustion and firefighters are inadvertently at risk of being exposed to these and other hazardous compounds. Exposure to PAHs is often estimated by measuring their hydroxylated metabolites (OH-PAH) in urine. Here, an online-SPE LC-MS-MS method was set up for eight OH-PAHs thus increasing sample throughput and minimizing manual handling. The method was validated over a 5-month period and showed good reproducibility with intra- and inter-day variation of 2.4-8.1 % and 1.6-6.5 %, respectively, of low-level samples and accuracy (91.6-104.8 %) for a standard reference material. The method was applied to urine samples from conscripts training to become firefighters to determine the optimal sampling time for this training activity before a large intervention study. In total, six conscripts sampled urine 6-8 times over a 40-hr period during a 3-day training course. All eight metabolites were detected in ≥ 97 % of the samples and showed peak excretion 4-6 hrs after the training corresponding to 8-10 hrs after first exposure. Samples taken the morning after the exercise contained low levels of most metabolites. Consequently, 4-6 hrs post exposure is recommended as the optimal sampling time for quantification of PAH exposure and monitoring of potential differences in exposure.

Low-dose acetylsalicylic acid for the prevention of pre-eclampsia.

Pre-eclampsia affects 3-4% of pregnancies and is associated with maternal and infant mortality and morbidity. High-risk pregnancies in Denmark are recommended prophylactic low-dose acetylsalicylic acid (LDA). If new screening algorithms are implemented, LDA will be recommended to around 10% of pregnant women. The use of LDA may slightly increase the risk of minor bleeding disturbances. Otherwise, there is a lot of promising data regarding the safety of LDA use during pregnancy, as argued in this review.

High-dose loco-regional pattern of failure after primary radiotherapy in p16 positive and negative head and neck squamous cell carcinoma - A DAHANCA 19 study.

Introduction: Patients with failure after primary radiotherapy (RT) for head and neck squamous cell carcinoma (HNSCC) have a poor prognosis. This study investigates pattern of failure after primary curatively intended IMRT in a randomized controlled trial in relation to HPV/p16 status. Material and methods: Patients with HNSCC of the oral cavity, oropharynx (OPSCC), hypopharynx or larynx were treated with primary curative IMRT (+/-cisplatin) and concomitant nimorazole between 2007 and 12. Of 608 patients, 151 had loco-regional failure within five years, from whom 130 pairs of scans (planning-CT and diagnostic failure scan) were collected and deformably co-registered. Point of origin-based pattern of failure analysis was conducted, including distance to CTV1 and GTV, and estimated dose coverage of the point of origin. Results: Of 130 patients with pairs of scans, 104 (80 %) had at least one local or regional failure site covered by 95 % of prescribed dose and 87 (67 %) of the failures had point of origin within the high-dose CTV (CTV1). Of failures from primary p16 + OPSCC, the majority of both mucosal (84 %) and nodal (61 %) failures were covered by curative doses. For p16- tumors (oral cavity, OPSCC p16neg, hypopharynx and larynx), 75 % of mucosal and 66 % of nodal failures were high-dose failures. Conclusion: Radioresistance is the primary cause of failure after RT for HNSCC irrespective of HPV/p16 status. Thus, focus on predictors for the response to RT is warranted to identify patients with higher risk of high-dose failure that might benefit from intensified treatment regimens.

Survey of Danish Head and Neck Cancer Patients' Positions on Personalized Medicine, Gene Tests, and Personalized Follow-Up.

The field of personalized medicine (PM) has grown rapidly because of the "omics revolution", but PM may be difficult for patients to comprehend. This study sought to explore head and neck cancer (HNC) patients' positions and knowledge of PM, gene tests, and follow-up and to compare HNC patients' positions to a sample from a national Danish questionnaire. To do this, patients with prior HNC were invited to participate in a questionnaire. Initial interviews revealed a heterogenic understanding of PM between patients. A total of 226 patients were included in the survey and 177 patients with complete data were included for analysis. Most patients were more positive than negative towards gene tests and gene research (83% and 93%, respectively), but 72% had little or no knowledge of the subject. Almost all patients, 98%, were satisfied with their follow-up. Significantly more patients with HNC were positive towards gene research compared to a sample from a national Danish questionnaire (p < 0.001). Patients with HNC were positive towards gene tests and PM, but patients may not understand or comprehend the information given, and it is important to inform and educate patients and health professionals to establish common ground in PM.

Tumor volume and cancer stem cell expression as prognostic markers for high-dose loco-regional failure in head and neck squamous cell carcinoma - A DAHANCA 19 study.

BACKGROUND AND PURPOSE: Reliable and accessible biomarkers for patients with Head and Neck Squamous Cell Carcinoma (HNSCC) are warranted for biologically driven radiotherapy (RT). This study aimed to investigate the prognostic value of putative cancer stem cell (CSC) markers, hypoxia, and tumor volume using loco-regional high-dose failure (HDF) as endpoint. MATERIALS AND METHODS: Tumor tissue was retrieved from patients treated with primary chemo-(C-)RT and nimorazole for HNSCC in the Danish Head and Neck Cancer Study Group (DAHANCA) 19 study. Tumor volume, hypoxic classification, and expression of CSC markers CD44, SLC3A2, and MET were analyzed. For patients with eligible data on all parameters (n = 340), the risk of HDF following primary chemo-(C-)RT were analyzed by these biomarkers as a whole and stratified for p16-positive oropharynx (p16 + OPSCC) vs p16-negative (p16-) tumors (oral cavity, p16- oropharynx, hypopharynx and larynx). RESULTS: Higher risk of HDF was seen for patients with larger primary and nodal volume (>25 cm3, Hazard Ratio (HR): 3.00 [95 % CI: 1.73-5.18]), high SLC3A2 (HR: 2.99 [1.28-6.99]), CD44 (>30 % positive, HR: 2.29 [1.05-5.00]), and p16- tumors (HR: 2.53 [1.05-6.11]). p16- tumors had a higher CSC marker expression than p16 + OPSCC. The factors associated with the highest risk of HDF were larger volume (HR: 3.29 [1.79-6.04]) for p16- tumors (n = 178) and high SLC3A2 (HR: 6.19 [1.58-24.23]) for p16 + OPSCC (n = 162). CONCLUSION: Tumor volume, p16, and CSC markers are potential biomarkers for HDF for patients with HNSCC treated with (C-)RT. Lower expression of CSC in p16 + OPSCC may contribute to better tumor control.

Evaluation of decentralised model-based selection of head and neck cancer patients for a proton treatment study. DAHANCA 35.

INTRODUCTION: Proton treatment can potentially spare patients with H&N cancer for substantial treatment-related toxicities. The current study investigated the reproducibility of a decentralised model-based selection of patients for a proton treatment study when the selection plans were compared to the clinical treatment plans performed at the proton centre. METHODS: Sixty-three patients were selected for proton treatment in the six Danish Head and Neck Cancer (DAHANCA) centres. The patients were selected based on normal tissue complication probability (NTCP) estimated from local photon and proton treatment plans, which showed a ΔNTCP greater than 5%-point for either grade 2 + dysphagia or grade 2 + xerostomia at six months. The selection plans were compared to the clinical treatment plans performed at the proton centre. RESULTS: Of the 63 patients, 49 and 25 were selected based on an estimated benefit in risk of dysphagia and xerostomia, respectively. Eleven patients had a potential gain in both toxicities. The mean ΔNTCP changed from the local selection plan comparison to the clinical comparison from 6.9 to 5.3 %-points (p = 0.01) and 7.3 to 4.9 %-points (p = 0.03) for dysphagia and xerostomia, respectively. Volume differences in both CTV and OAR could add to the loss in ΔNTCP. 61 of the 63 clinical plans had a positive ΔNTCP, and 38 had a ΔNTCP of 5%-points for at least one of the two endpoints. CONCLUSION: A local treatment plan comparison can be used to select candidates for proton treatment. The local comparative proton plan overestimates the potential benefit of the clinical proton plan. Continuous quality assurance of the delineation procedures and planning is crucial in the subsequent randomised clinical trial setting.

HPV testing versus p16 immunohistochemistry in oropharyngeal squamous cell carcinoma: results from the DAHANCA 19 study.

INTRODUCTION: The prognosis after primary (chemo-)radiotherapy for oropharyngeal squamous cell carcinoma (OPSCC) is affected by Human Papillomavirus (HPV) status, with a better prognosis in HPV-positive OPSCC. HPV-status is routinely assessed by p16 immunohistochemistry (IHC), but additional HPV DNA testing is debated. Also, there are numerous HPV genotypes, which prognostic role may need clarification. The purpose of this study was: (1) to test a custom-made targeted HPV next generation sequencing (NGS) panel in OPSCC, (2) to determine correlation with p16 IHC, and (3) to assess the impact of HPV DNA testing on outcome in the prospectively randomized clinical trial DAHANCA 19. MATERIALS AND METHODS: We included 271 patients with OPSCC treated with primary (chemo-)radiotherapy in the DAHANCA 19 trial. Of these, 199 (73%) were p16-positive. HPV-status was determined by targeted HPV next generation sequencing (NGS), using a custom-made HPV genotyping panel. RESULTS: HPV was detected in 194 tumor samples. p16 IHC and NGS HPV status were concordant in 265 (98%) of 271 patients, whereas we did not detect HPV DNA in 5 p16-positive tumors. HPV16 accounted for 169 of 194 HPV-positive cases (87%). HPV genotypes 18, 31, 33, 35, and 59 were also detected.Loco-regional failure and overall survival were similar whether patients were separated by p16 IHC, or HPV DNA status (p < 0.0001 for all) and did not depend on HPV genotype (p = 0.9 and p = 0.7). CONCLUSION: In the present study, HPV DNA testing or typing in a Danish OPSCC cohort did not add additional information to p16 IHC, the most widely used and accepted prognostic indicator.

Socioeconomic position and the pre-diagnostic interval among patients diagnosed with head and neck squamous cell carcinoma - a population-based study from DAHANCA.

BACKGROUND: The socioeconomic differences in survival are pronounced for patients diagnosed with head and neck cancer; disease stage at diagnosis is suggested to be a main driver of this association. This nationwide, population-based study investigates socioeconomic differences in the pre-diagnostic interval and disease stage at diagnosis. MATERIAL AND METHODS: Information on patient-reported symptoms, symptom onset and disease-specific factors was obtained from the nationwide population-based Danish Head and Neck Cancer Group (DAHANCA) database for patients diagnosed with head and neck squamous cell carcinoma between 2008 and 2019 in Denmark. Socioeconomic position (SEP) was measured by individual-level education, income and cohabitation status obtained from administrative registers. Socioeconomic differences in the interval from symptom onset to diagnosis were investigated in general linear models with 95% confidence intervals (CIs); overall and by subsite, symptom and comorbidity score. Consultation patterns prior to diagnosis were examined using methods for change-point detection. Associations with advanced-stage disease were estimated in logistic regression models. RESULTS: Patients with low, medium and high SEP had a similar interval from patient-reported symptom onset to diagnosis of 10 weeks. Although this interval varied according to primary symptom and anatomical subsite, no apparent socioeconomic differences were observed within these subgroups. Aligned with the patient-reported symptom onset, a distinct increase in consultation rates was observed at 9 weeks (95% CI [7.3; 10.7]) for patients with low SEP and 7 weeks (95% CI [4.8; 9.2]) for patients with high SEP, with overlapping CIs. Patients with low compared to high SEP had increased odds for advanced-stage glottic and oral cavity squamous cell carcinoma. For the remaining subsites the association varied according to SEP-indicator and TNM-edition. CONCLUSION: The interval from symptom onset to diagnosis and consultation patterns were similar across SEP groups. Still, socioeconomic differences in stage at diagnosis were observed for some - but not all - subsites.

Consistency in contouring of organs at risk by artificial intelligence vs oncologists in head and neck cancer patients.

BACKGROUND: In the Danish Head and Neck Cancer Group (DAHANCA) 35 trial, patients are selected for proton treatment based on simulated reductions of Normal Tissue Complication Probability (NTCP) for proton compared to photon treatment at the referring departments. After inclusion in the trial, immobilization, scanning, contouring and planning are repeated at the national proton centre. The new contours could result in reduced expected NTCP gain of the proton plan, resulting in a loss of validity in the selection process. The present study evaluates if contour consistency can be improved by having access to AI (Artificial Intelligence) based contours. MATERIALS AND METHODS: The 63 patients in the DAHANCA 35 pilot trial had a CT from the local DAHANCA centre and one from the proton centre. A nationally validated convolutional neural network, based on nnU-Net, was used to contour OARs on both scans for each patient. Using deformable image registration, local AI and oncologist contours were transferred to the proton centre scans for comparison. Consistency was calculated with the Dice Similarity Coefficient (DSC) and Mean Surface Distance (MSD), comparing contours from AI to AI and oncologist to oncologist, respectively. Two NTCP models were applied to calculate NTCP for xerostomia and dysphagia. RESULTS: The AI contours showed significantly better consistency than the contours by oncologists. The median and interquartile range of DSC was 0.85 [0.78 - 0.90] and 0.68 [0.51 - 0.80] for AI and oncologist contours, respectively. The median and interquartile range of MSD was 0.9 mm [0.7 - 1.1] mm and 1.9 mm [1.5 - 2.6] mm for AI and oncologist contours, respectively. There was no significant difference in ΔNTCP. CONCLUSIONS: The study showed that OAR contours made by the AI algorithm were more consistent than those made by oncologists. No significant impact on the ΔNTCP calculations could be discerned.

Sample Preparation for Metabolite Detection in Mass Spectrometry Imaging.

Metabolites reflect the biological state of cells and tissue, and metabolomics is therefore a field of high interest both to understand normal physiological functions and disease development. When studying heterogeneous tissue samples, mass spectrometry imaging (MSI) is a valuable tool as it conserves the spatial distribution of analytes on tissue sections. A large proportion of metabolites are, however, small and polar, making them vulnerable to delocalizing through diffusion during sample preparation. Here we present a sample preparation method optimized to limit diffusion and delocalization of small polar metabolites in fresh frozen tissue sections. This sample preparation protocol includes cryosectioning, vacuum frozen storage, and matrix application. The methods described were primely developed for matrix-assisted laser desorption/ionization (MALDI) MSI, but the protocol describing cryosectioning and vacuum freezing storage can also be applied before desorption electrospray ionization (DESI) MSI. Our vacuum drying and vacuum packing approach offers a particular advantage to limit delocalization and safe storage.

Visualization of Small Intact Proteins in Breast Cancer FFPE Tissue.

Molecular visualization of metabolites, lipids, and proteins by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is becoming an in-demand analytical approach to aid the histopathological analysis of breast cancer. Particularly, proteins seem to play a role in cancer progression, and specific proteins are currently used in the clinic for staging. Formalin-fixed paraffin-embedded (FFPE) tissues are ideal for correlating the molecular markers with clinical outcomes due to their long-term storage. So far, to obtain proteomic information by MSI from this kind of tissue, antigen retrieval and tryptic digestion steps are required. In this chapter, we present a protocol to spatially detect small proteins in tumor and necrotic regions of patient-derived breast cancer xenograft FFPE tissues without employing any on-tissue digestion. This protocol can be used for other kinds of FFPE tissue following specific optimization of the sample preparation phases.

Epidemiology, outcomes, and prognostic factors in submandibular gland carcinomas: a national DAHANCA study.

PURPOSE: The aim of this study is to present incidence, histological subtypes, survival rates, and prognostic factors based on a national cohort of patients with salivary gland carcinoma. METHODS: All Danish patients with submandibular gland carcinoma diagnosed from 1990 to 2015 (n = 206) were included and analyzed following histological re-evaluation. Data were collected by the Danish Head and Neck Cancer Group (DAHANCA). Overall, disease-specific and recurrence-free survival were evaluated. Prognostic factors were analyzed with multivariate Cox Hazard Regression. RESULTS: The study population consisted of 109 (53%) men and 97 (47%) women, median age 62 years (range 11-102). Adenoid cystic carcinoma was the most frequent subtype (50%). Tumour classification T1/T2 (75%) and N0 (78%) was most frequent. The mean crude incidence was 0.17/100,000/year. Most patients (n = 194, 94%) were treated with primary surgery, and 130 (67%) received postoperative radiotherapy. The 5- and 10-year survival rates were for overall survival 64% and 41%, disease-specific survival 74% and 61%, and recurrence-free survival 70% and 56%, respectively. Survival rates were higher for adenoid cystic carcinoma compared to other subtypes, but the difference was not significant in multivariate analysis. Recurrence occurred in 69 patients, and 37 (53.6%) of them had recurrence in a distant site. Advanced T-classification and regional lymph-node metastases had significant negative impact on survival rates. CONCLUSION: The incidence of submandibular gland carcinoma in Denmark was 0.17/100,000/year and stable during the time period. The most frequent subtype was adenoid cystic carcinoma. Half of the recurrences presented in a distant site, and multivariate analysis confirmed that advanced stage was independent negative prognostic factor for recurrence and survival.

A Circular RNA Expressed from the FAT3 Locus Regulates Neural Development.

Circular RNAs (circRNAs) are key regulators of cellular processes, are abundant in the nervous system, and have putative regulatory roles during neural differentiation. However, the knowledge about circRNA functions in brain development is limited. Here, using RNA-sequencing, we show that circRNA levels increased substantially over the course of differentiation of human embryonic stem cells into rostral and caudal neural progenitor cells (NPCs), including three of the most abundant circRNAs, ciRS-7, circRMST, and circFAT3. Knockdown of circFAT3 during early neural differentiation resulted in minor transcriptional alterations in bulk RNA analysis. However, single-cell transcriptomics of 30 and 90 days differentiated cerebral organoids deficient in circFAT3 showed a loss of telencephalic radial glial cells and mature cortical neurons, respectively. Furthermore, non-telencephalic NPCs in cerebral organoids showed changes in the expression of genes involved in neural differentiation and migration, including FAT4, ERBB4, UNC5C, and DCC. In vivo depletion of circFat3 in mouse prefrontal cortex using in utero electroporation led to alterations in the positioning of the electroporated cells within the neocortex. Overall, these findings suggest a conserved role for circFAT3 in neural development involving the formation of anterior cell types, neuronal differentiation, or migration.

Regional divergence and time trends in the prevalence of gestational diabetes mellitus: a national Danish cohort study.

AIMS: To evaluate the prevalence and time trends of gestational diabetes mellitus (GDM) across the five regions of Denmark with uniform national guidelines for screening and diagnosing GDM. METHODS: This register-based national cohort study included 287,684 births from 2013 to 2017. Trends in GDM prevalence over time and differences between the five regions were evaluated. Crude and adjusted odd ratios (ORs) for GDM were calculated including potential confounding clinical risk factors as age, BMI, educational level, marital status, parity, country of origin and assisted reproduction. RESULTS: From 2013 to 2017, GDM prevalence in Denmark increased by 7% per year (OR 1.07, 95% CI 1.06-1.09, P < 0.001). GDM prevalence varied considerably between regions and ranged from 3.0 to 5.9% in 2017, corresponding to a maximal regional difference of 97%. In crude analyses, the risk of GDM in 2017 was significantly different in four of five regions compared to the remaining regions (OR ranging from 0.60 to 1.55), and these differences persisted after adjusting for confounding clinical risk factors (adjusted OR: 0.59-1.45). CONCLUSION: The prevalence of GDM increased over time in all Danish regions with substantial regional divergence. Up to a 97%, difference in GDM prevalence was observed between Danish regions, which was not explained by available clinical risk factors. This occurred despite national guidelines and raises the question of whether regional variations in screening efficacy, diagnostic procedures or inequality in clinical health care access may explain the observed differences.

Association of Smoking, Comorbidity, Clinical Stage, and Treatment Intent With Socioeconomic Differences in Survival After Oropharyngeal Squamous Cell Carcinoma in Denmark.

Importance: The socioeconomic gap in survival after cancer is pronounced among patients with head and neck cancer. Understanding the mechanisms of this gap is crucial to target intervention strategies. Objective: To investigate socioeconomic differences in survival after oropharyngeal squamous cell carcinoma (OPSCC) according to human papillomavirus (HPV) status and the extent to which smoking, comorbidity, clinical stage, and treatment intent explain the survival gap. Design, Setting, and Participants: This nationwide, population-based cohort study was based on prospectively collected information on all patients with a diagnosis of OPSCC from the Danish Head and Neck Cancer Group database and administrative registries. The study included 4600 patients born in 1921 or later, aged 30 years or older, and residing in Denmark 1 year prior to OPSCC diagnosis. Patients with missing information (547 [12%]) were excluded. Patients were diagnosed between January 1, 2008, and December 31, 2019, and followed up until December 31, 2021. Data were analyzed from June 6 to October 4, 2022. Exposure: Socioeconomic position (educational level, disposable income, or cohabiting status). Main Outcomes and Measures: Socioeconomic differences in 5-year overall survival were estimated in Cox proportional hazards regression models by HPV status. The indirect effect and proportion mediated by smoking, comorbidity, clinical stage, and treatment intent were estimated based on a counterfactual approach. Results: The analyzed cohort comprised 4053 patients (1045 women [26%] and 3008 men [74%]). The median age was 61 years (IQR, 55-68 years), and 2563 patients (63%) had HPV-positive OPSCC while 1490 patients (37%) had HPV-negative OPSCC. The 5-year standardized overall survival was 10% to 15% lower among patients with a lower educational level, with low disposable income, or who were living alone (patients with HPV-positive OPSCC, 68%-71%; patients with HPV-negative OPSCC, 31%-34%) than patients with a higher educational level, high disposable income, or a cohabiting partner (patients with HPV-positive OPSCC, 81%-86%; patients with HPV-negative OPSCC, 43%-46%). Among patients with HPV-positive OPSCC, a considerable part of this survival gap was estimated to be associated with differences in smoking (27%-48%), comorbidity (10%-19%), clinical stage (8%-19%), and treatment intent (16%-28%). Among those with HPV-negative OPSCC, comorbidity (12%-22%) and treatment intent (16%-42%) were the primary potential mediators. Conclusions and Relevance: This cohort study suggests that, regardless of HPV status, patients with low socioeconomic position had 10% to 15% lower 5-year overall survival than patients with high socioeconomic position. A substantial part of this survival gap was associated with differences in smoking, comorbidity, clinical stage, or treatment intent at diagnosis.

Pediatric Celiac Disease and Selective IgA Deficiency: Unexpected Sequence of Events.

PURPOSE: Selective IgA deficiency (IgAD) is the most common primary immunodeficiency, frequently leading to only minor clinical complaints. IgAD may be associated with autoimmune diseases such as celiac disease (CeD). Although IgAD is thought to precede CeD and autoimmunity, the association between the two conditions has not been clarified. METHODS: Routine techniques were used to measure serum IgA and celiac diagnostic markers as transglutaminase 2 IgA (TG2-IgA) and deamidated gliadin IgG and for immunohistochemistry for IgG, IgM, and IgA. RESULTS: We report two childhood cases of complete IgA deficiency that evolved after the diagnosis of CeD and the start of a gluten-free diet. Histology showed persistence of IgA in the intestinal mucosa. CONCLUSION: Both children with CeD showed IgA deficiency that unexpectedly developed after the initiation of a gluten-free diet. This supports IgA deficiency as a process that develops gradually and occurs due to specific defects in immunoregulation.