Application of a Computational Metabolomics Workflow for the Diagnosis of Inborn Errors of Metabolism in a Laboratory Setting.

Inborn errors of metabolism constitute a set of hereditary diseases that impose severe medical and physical challenges in the affected individual, in particular, for the pediatric patient population. Timely diagnosis is crucial for these patients, as any delay could result in irreversible health damage, underscoring the importance of early initiation of personalized treatment. Current routine diagnostic screening for inborn errors of metabolism relies on various targeted analyses of established biomarkers. However, this approach is time-consuming, focuses on a limited number of tests (based on clinical information) with a relatively small number of biomarkers, and does not facilitate the identification of new markers. In contrast, untargeted metabolomics-based screening offers a more efficient diagnostic solution, by assessing thousands of metabolites across multiple metabolic pathways in a single test. This not only saves time but also conserves resources for clinicians, the diagnostic laboratory, and for patients.This chapter describes the computational workflow of our "Next Generation Metabolic Screening" approach, which is a metabolomics-based method that is currently applied at the Translational Metabolic Laboratory of the Radboud University Medical Center (the Netherlands) for the diagnosis of inborn errors of metabolism.

Decoding mutational hotspots in human disease through the gene modules governing thymic regulatory T cells.

Computational strategies to extract meaningful biological information from multiomics data are in great demand for effective clinical use, particularly in complex immune-mediated disorders. Regulatory T cells (Tregs) are essential for immune homeostasis and self-tolerance, controlling inflammatory and autoimmune processes in many diseases with a multigenic basis. Here, we quantify the Transcription Factor (TF) differential occupancy landscape to uncover the Gene Regulatory Modules governing lineage-committed Tregs in the human thymus, and show that it can be used as a tool to prioritise variants in complex diseases. We combined RNA-seq and ATAC-seq and generated a matrix of differential TF binding to genes differentially expressed in Tregs, in contrast to their counterpart conventional CD4 single-positive thymocytes. The gene loci of both established and novel genetic interactions uncovered by the Gene Regulatory Modules were significantly enriched in rare variants carried by patients with common variable immunodeficiency, here used as a model of polygenic-based disease with severe inflammatory and autoimmune manifestations. The Gene Regulatory Modules controlling the Treg signature can, therefore, be a valuable resource for variant classification, and to uncover new therapeutic targets. Overall, our strategy can also be applied in other biological processes of interest to decipher mutational hotspots in individual genomes.

Isolated methylmalonic acidemia in Mexico: Genotypic spectrum, report of two novel MMUT variants and a possible synergistic heterozygosity effect.

Isolated methylmalonic acidemia (iMMA) is a group of monogenic metabolic disorders affecting methylmalonate and cobalamin metabolism. Five iMMA-responsible genes have been described to date: MMUT (MIM *609058), MMAA (MIM *607481, MMAB (MIM *607568), MMADHC (MIM *611935), and MCEE (MIM *608419). Although iMMA is the most common form of organic acidemia reported in Mexico, its genotypic spectrum is still largely unknown. We performed a clinical exome analysis on 42 unrelated Mexican patients with iMMA. MMUT deficiency accounted for 73.8 % of all cases, followed by MMAA (14.2 %), MMAB (7.2 %), and MMADHC (2.4 %) deficiencies. One patient presented MMUT and MMAA double heterozygosity, which should be further experimentally confirmed to prove that synergistic heterozygosity could be another inheritance mechanism in iMMA. The most frequent MMUT genotype involved the Hispanic variant NM_000255.4:c. [322C > T];[322C > T] or p.[Arg108Cys];[Arg108Cys] (14.3 %). Two novel MMUT variants, NM_000255.4:c.589G > A or p.(Ala197Thr) and c.1476C > A or p.(Tyr492*), were identified in a deceased newborn presenting the neonatal-onset severe form of the disease. In silico protein modeling of the p.(Arg108Cys) and novel p.(Ala197Thr) MMUT variants suggested disruption of the substrate-binding and catalytic domains of the protein, respectively. This study expands the current knowledge on the molecular spectrum of iMMA in the Mexican population and reinforces the importance of genetic analysis in guiding clinical management.

UBTF haploinsufficiency associated with UBTF-related global developmental delay and distinctive facial features without neuroregression.

BACKGROUND: The Upstream Binding Transcription Factor (UBTF) gene encodes two nucleolar proteins, UBTF1 and UBTF2. UBTF1 regulates rRNA transcription by RNA polymerase I, while UBTF2 regulates mRNA transcription by RNA polymerase II. A recurrent de novo dominant mutation c.628G>A (p.Glu210Lys) has been identified as a gain-of-function mutation associated with childhood onset neurodegeneration with brain atrophy (CONDBA). Evidence from large-scale population databases and Ubtf+/- mouse models indicates that UBTF haploinsufficiency is not tolerated. METHODS: Three unrelated patients with global developmental delay and distinctive facial features were recruited for the study. Whole exome sequencing (WES) was performed to identify potential genetic abnormalities. Additionally, copy number variation analysis was conducted based on the WES data. RESULTS: All three patients exhibited intellectual disabilities, social challenges and developmental delays in language and gross motor skills. Distinctive facial features included a wide forehead, sparse eyebrows, hypertelorism, narrow palpebral fissures, single-fold eyelids, a flat nasal bridge, anteverted nares, a long philtrum and a thin upper lip. Additionally, patient C presented with more severe language delay, recurrent hepatic dysfunction and an atrial septal defect. Patient A was found to have a nonsense variant, c.1327C>T (p.R443Ter), in the exon 13 of UBTF. Patients B and C both carried a heterozygous deletion encompassing the UBTF gene. CONCLUSION: In this study, we analysed the detailed phenotypes associated with UBTF haploinsufficiency, which, to our knowledge, have not been previously reported. We propose that UBTF haploinsufficiency-related global developmental delay and distinctive facial features, without neuroregression, constitute a new syndrome distinct from CONDBA.

A genome-wide association study of adults with community-acquired pneumonia.

BACKGROUND: Community-acquired pneumonia (CAP) is associated with high morbidity and hospitalization rate. In infectious diseases, host genetics plays a critical role in susceptibility and immune response, and the immune pathways involved are highly dependent on the microorganism and its route of infection. Here we aimed to identify genetic risk loci for CAP using a case-control genome-wide association study (GWAS). METHODS: We performed a GWAS on 3,765 Spanish individuals, including 257 adult patients hospitalized with CAP and 3,508 population controls. Pneumococcal CAP was documented in 30% of patients; the remaining 70% were selected among patients with unidentified microbiological etiology. We tested 7,6 million imputed genotypes using logistic regressions. UK Biobank GWAS of bacterial pneumonia were used for results validation. Subsequently, we prioritized genes and likely causal variants based on Bayesian fine mapping and functional evidence. Imputation and association of classical HLA alleles and amino acids were also conducted. RESULTS: Six independent sentinel variants reached the genome-wide significance (p < 5 × 10-8), three on chromosome 6p21.32, and one for each of the chromosomes 4q28.2, 11p12, and 20q11.22. Only one variant at 6p21.32 was validated in independent GWAS of bacterial and pneumococcal pneumonia. Our analyses prioritized C4orf33 on 4q28.2, TAPBP on 6p21.32, and ZNF341 on 20q11.22. Interestingly, genetic defects of TAPBP and ZNF341 are previously known inborn errors of immunity predisposing to bacterial pneumonia, including pneumococcus and Haemophilus influenzae. Associations were all non-significant for the classical HLA alleles. CONCLUSIONS: We completed a GWAS of CAP and identified four novel risk loci involved in CAP susceptibility.

Management of a Patient with Cardiovascular Disease Should Include Assessment of Primary and Secondary Immunodeficiencies: Part 1-Primary Immunodeficiencies.

BACKGROUND: Cardiovascular diseases are some of the most prevalent chronic diseases that generate not only high social but also economic costs. It is becoming increasingly crucial to take into account inborn errors of immunity (IEIs, formerly known as primary immunodeficiencies (PIDs)) and secondary immunodeficiencies (SIDs) in the diagnostic and therapeutic management of cardiac patients. The number of diseases classified as IEIs is on the rise, with a current total of 485. It is essential to pay attention not only to already confirmed conditions but also to symptoms suggestive of immunodeficiencies. OBJECTIVES: The aim of this article is to present IEIs with cardiovascular symptoms that may cause or exacerbate cardiovascular disease, as well as diagnostic and therapeutic procedures. RESULTS: It is becoming increasingly evident that immunodeficiencies can be responsible for certain cardiovascular conditions, their hastened progression, and difficulties in their control. CONCLUSIONS: Early detection of deficiencies improves not only the quality and longevity of patients, but also allows for better control of cardiovascular diseases and even prevention of their occurrence.

Cancer Trends in Inborn Errors of Immunity: A Systematic Review and Meta-Analysis.

BACKGROUND: Patients with inborn errors of immunity (IEI) are susceptible to developing cancer due to defects in the immune system. The prevalence of cancer is higher in IEI patients compared to the immunocompetent population and cancers are considered as an important and common cause of death in IEI patients. OBJECTIVES: To systematically review demographic, genetic and cancer-related data of IEI patients with a history of malignancy. Moreover, we performed a meta-analysis aiming to determine the frequency of cancer in patients with different types of IEI. METHODS: We conducted electronic searches on Embase, Web of Science, PubMed, and Scopus (until September 2023) introducing terms related to IEI and cancer. Studies with human subjects with confirmed IEI who had developed at least one malignancy during their lifetime were included. RESULTS: A total number of 4607 IEI patients with a cancer history were included in the present study. Common variable immunodeficiency (CVID) had the highest number of reported cases (1284 cases), mainly due to a higher relative proportion of patients with predominantly antibody deficiencies (PAD) and their increased life expectancy contributing to the higher detection and reporting of cancers among these patients. The most common malignancy was hematologic/blood cancers (3026 cases, mainly diffuse large B cell lymphoma). A total number of 1173 cases (55.6%) succumbed to cancer, with the highest rate of bone marrow failure (64.9%). Among the patients with monogenic defects in IEI-associated genes, the majority of cases had ATM deficiency (926 cases), but the highest cancer frequency rate belonged to NBS1 deficiency (50.5%). 1928 cases out of total 4607 eligible cases had detailed data to allow further statistical analysis that revealed BRCA2 deficiency had the earliest cancer development (~ 38 months), lowest cure frequency, and highest fatality rate (85%), while ATM deficiency had the lowest cure frequency and highest fatality rate (72%) among total cases reviewed with exclusion of Fanconi anemia. CONCLUSION: The overall reported cancer frequency in the cases reviewed with and without exclusion of Fanconi anemia was 11.1% (95% confidence interval: 9.8-12.5%) and 12.0% (95% confidence interval: 10.6-13.5%), respectively. Our study revealed that the incidence of cancer is significantly dependent on the molecular and pathway defects in IEI patients, and individualized early screening and appropriate treatment, might improve the prognosis of these patients.

THYMIC INBORN ERRORS OF IMMUNITY.

The thymus is crucial for optimal T cell development by facilitating the generation and selection of a diverse repertoire of T cells that can recognize foreign antigens while promoting tolerance to self-antigens. A number of inborn errors of immunity (IEI) causing complete or partial defects in thymic development (athymia) and/or impaired thymic function have been increasingly recognized that manifest clinically with a combination of life-threatening infections, severe multiorgan autoimmunity, and/or cardiac, cranio-facial, ectodermal, and endocrine abnormalities. The introduction of newborn screening programs and the advent of thymic transplantation show promise for early detection and improving the outcomes of patients with certain thymic IEI. Herein, we discuss our current understanding of the genetics, immunopathogenesis, diagnosis, and treatment of IEI that impair thymic development and/or function.

Family Lore, a Variant of Uncertain Significance, and CADASIL.

An infant presents in extremis. After the medical team stabilizes him, the race is on to figure out why he got so sick in the first place. The consulting genetics team thinks that it is unlikely his problems are due to a genetic cause, but his extreme, confounding presentation is enough to justify trio exome sequencing. When the results reveal an unexpected, paternally inherited variant of uncertain significance (VUS) in NOTCH3, fresh questions arise. The infant's presenting symptoms and descriptive diagnoses, including hematemesis, epistaxis, and gastric ulcers, certainly do not fit the mold of CADASIL. However, closer inspection of his family history yields tantalizing clues: a father and paternal grandfather with seizures, and a paternal grandfather with unexplained mood disturbances in middle age. Combining details gleaned from the family history and medical literature, the clinical genetics and laboratory genetics team collaborated, reclassified the VUS as likely pathogenic, and offered a new unifying diagnosis to explain much of the family's lore.

Microbial Isolates and Antimicrobial Resistance Patterns in Adults with Inborn Errors of Immunity: A Retrospective Longitudinal Analysis of Sputum Cultures.

INTRODUCTION: Individuals with inborn errors of immunity (IEI) are at increased risk of respiratory infection and frequently receive prolonged broad-spectrum antibiotics, leading to antibiotic resistance. The aim of this study was to identify respiratory pathogens and antibiotic resistance patterns in IEI patients. METHODS: We retrospectively studied 36 IEI patients with positive bacterial growth in sputum cultures between 2014 and 2023. Data covered hospitalizations, respiratory infections, yearly antibiotic prescriptions, past sputum cultures, and antibiotic sensitivities. Patients with primary ciliary dyskinesia (PCD) and bronchiectasis served as a control group. RESULTS: A total of 314 sputum cultures were analyzed from patients with IEI, alongside 585 cultures from individuals with PCD and 113 cultures from patients with bronchiectasis. Patients with IEI had a median age of 23.5 years, with 61% male participants. The study compared the differences in bacterial isolates from sputum cultures and antibiotic resistance between patients with IEI and the control groups. The most common bacterial isolates across all groups were Haemophilus influenzae (159 isolates in IEI vs. 314 in PCD and 26 in bronchiectasis), Pseudomonas aeruginosa, and Streptococcus pneumoniae. In IEI patients, 992 symptomatic respiratory exacerbations and 43 pneumonia-related hospitalizations were recorded. Notably, H. influenzae in IEI patients showed high resistance rates to cefuroxime (82%), amoxicillin/clavulanic acid (66%), trimethoprim/sulfamethoxazole (59%), and ampicillin/sulbactam (49%). P. aeruginosa in IEI patients displayed significant resistance to ciprofloxacin (85%), ceftazidime (42%), and aminoglycosides (23-33%). Additionally, all S. pneumoniae isolates in IEI patients were tetracycline resistant, with high resistance rates to penicillin, clindamycin, and erythromycin. It is essential to highlight the substantial resistance of common pathogens to oral antibiotics. In contrast, the control groups exhibited lower resistance rates across all bacterial isolates. CONCLUSION: Antimicrobial resistance is a growing concern among vulnerable IEI patients. We suggest conducting similar investigations in other regions to address this issue. The findings should inform future infection management guidelines for IEIs.

Inborn Errors of Immunity-related Immunological Mechanisms and Pharmacological Therapy Alternatives in Periodontitis.

Periodontitis is a frequent local inflammatory disease. The microbiota and repeated exposure to bacterial endotoxins triggers excessive inflammation through oral mucosal immunity, sometimes leading to a destructive effect on the supportive mucosal tissues around the teeth. Elimination of the pathogens and increasing the tolerance of the cellular immune response is crucial in addition to standard dental therapies like mechanical debridement. Based on our experience on immune-mediated diseases, especially primary immunodeficiency diseases (PIDs), we wrote this review to discuss the treatment alternatives for severe periodontal disease. Risk factors are malnutrition, vitamin deficiencies, smoking, systemic inherited and acquired immune-mediated diseases, infections, endocrinological diseases, and pharmacological agents may accompany periodontitis. The diagnosis and treatment of dietary deficiencies, as well as the addition of nutritional supplements, may aid in epithelial regeneration and immune system function. Recently, modifications to the therapeutic option for severe periodontitis have been made depending on the fact that the immune response against bacteria may modify the severity of periodontal inflammation. The anti-inflammatory therapies support or inhibit the host's immune response. The clinical approach to severe periodontitis should extend beyond classical therapies. There is a need for a diverse therapeutic strategy that supports the epithelial barrier, which is the crucial component of innate immunity against microbiota. Leukocytes are the main cellular component in periodontal inflammation. Anti-inflammatory therapeutic options directed at leukocytes, such as IL-17 and IL-23-targeted therapies, could be the candidates for the treatment of severe periodontitis. Therapy against other inflammatory cytokines, IL-1, IL-6, IL12, IL23, TNF-alpha, PGE2, and cytokine receptors, could also be used in periodontal inflammation control.

Fecal microbiota transplantation in a patient with chronic diarrhea and primary and secondary immunodeficiency (common variable immunodeficiency and splenectomy).

The gut microbiota serves a crucial role in the development of host immunity. Immunocompromised patients are particularly vulnerable to dysbiosis not only by virtue of a defect in the immune system but also due to increased susceptibility to infection and multiple courses of antibiotic therapy. Fecal microbiota transplantation is by far the most effective option for restoring gastrointestinal homeostasis. However, it is contraindicated in patients with significant primary and secondary immunodeficiencies. This article presents the case of a 59-year-old patient with common variable immunodeficiency, after splenectomy at age 39 for primary immune thrombocytopenia, who manifested diarrhea of up to 10 stools per day accompanied by secondary malnutrition and cachexia. The patient was admitted to the hospital on multiple occasions due to this condition, with stool PCR tests confirming a HHV-5 (Cytomegalovirus, CMV) infection. Following the administration of valganciclovir, the patient's complaints diminished, although, upon cessation of the drug, the symptoms recurred. In addition, the patient had an intestinal infection with C. difficile etiology. Given that the patient's therapeutic options had been exhausted, after obtaining informed consent from the patient and approval from the bioethics committee to conduct a medical experiment, treatment of diarrhea was undertaken by fecal microbiota transplantation with the certified preparation Mbiotix HBI from the Human Biome Institute. The patient underwent two transplants, with a one-week interval between them. The initial procedure was performed using the endoscopic method, while the subsequent was conducted using the capsule method. Following the administration of the applied treatment, the patient's symptoms were successfully alleviated, and no adverse effects were observed. A microbiological analysis of the intestinal microbiota was conducted prior to and following transplantation via next-generation sequencing (NGS). No recurrence of symptoms was observed during the two-year follow-up period. To the best of our knowledge, this is the first fecal microbiota transplantation in an adult patient with primary and secondary immunodeficiency.

Perinatal management and follow-up in a child with a prenatal diagnosis of OTC deficiency: a case report.

Ornithine transcarbamylase deficiency (OTCD) is the most common disorder of the urea cycle and is caused by a mutation of the OTC gene, located on chromosome X. Its prevalence is estimated at 1 in 80,000 to 56,500 births, but this X-chromosomal inheritance results in males being more affected than females. In neonates affected with this disorder, hyperammonemia after birth can lead to neurological and liver damage that can be fatal. We present a child with a prenatal diagnosis based on an older sibling with the same pathology, which led us to adopt an intensive treatment since the delivery. He was admitted in a neonatal unit and treatment with protein restriction, 10% glucose saline serum and glycerol phenylbutyrate was initiated. To date, after 3.5 years of follow up, growth and neurological development have been adequate, biochemical control has been appropriate except for a simple and mild decompensation during the course of a gastroenteritis. This case emphasises the importance of early diagnosis and treatment to avoid potential complications.

Incidence of Inborn Errors of Metabolism and Endocrine Disorders Among 40965 Newborn Infants at Riyadh Second Health Cluster of the Ministry of Health Saudi Arabia.

Inborn errors of metabolism (IEM) and endocrine disorders are common genetic conditions in the Saudi population with the incidence rate often underestimated. Newborn screening (NBS) using various disease panels provides the first line in the early detection and intervention among infants with a high risk of IEM. Here we aim to assess the incidence of screening disorders and provide an overview of the NBS program at the Ministry of Health Tertiary Care King Fahad Medical City. Dried blood spots (DBS) from 40,965 newborn infants collected on the second day after birth were analyzed for 20 disorders. The total number of positive screen ("repeat") samples over 10 years was about 1% (n = 382/40,965). The true positive result rate was 15.3% (n = 46/301) with the recall rates of individual disorders ranging from 0.26% (95% CI, 0.17-0.69) to 2.6% (95% CI, 2.19-3.05). The false positive result rate was 84.7% (n = 255/301) with biotinidase activity found to be the most common cause of the second sample repeat. The overall incidence of the screened diseases was 1:891 (95% CI, 11.61-12.47). CH and CAH are the most prevalent among endocrine disorders with an incidence of 1:4097 (95% CI, 2.19-3.05), and PA and ASA among the IEM with an incidence of 1:10,241 (95% CI, 0.09-0.95). In summary, we provide updated data and our experience on the incidence of various IEM and endocrine disorders among the Saudi population, highlight the role of false positive results of biotinidase activity that can increase the recall rate and lead to overestimation of the incidence data, and recommend multicenter studies to achieve a successful national NBS program.

Pathophysiology of Congenital High Production of IgE and Its Consequences: A Narrative Review Uncovering a Neglected Setting of Disorders.

Elevated serum IgE levels serve as a critical marker for uncovering hidden immunological disorders, particularly inborn errors of immunity (IEIs), which are often misdiagnosed as common allergic conditions. IgE, while typically associated with allergic diseases, plays a significant role in immune defense, especially against parasitic infections. However, extremely high levels of IgE can indicate more severe conditions, such as Hyper-IgE syndromes (HIES) and disorders with similar features, including Omenn syndrome, Wiskott-Aldrich syndrome, and IPEX syndrome. Novel insights into the genetic mutations responsible for these conditions highlight their impact on immune regulation and the resulting clinical features, including recurrent infections, eczema, and elevated IgE. This narrative review uniquely integrates recent advances in the genetic understanding of IEIs and discusses how these findings impact both diagnosis and treatment. Additionally, emerging therapeutic strategies, such as hematopoietic stem cell transplantation (HSCT) and gene therapies, are explored, underscoring the potential for personalized treatment approaches. Emphasizing the need for precise diagnosis and tailored interventions aims to enhance patient outcomes and improve the quality of care for those with elevated IgE levels and associated immunological disorders.

JAK-STAT signaling pathway, immunodeficiency, inflammation, immune dysregulation, and inborn errors of immunity.

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling cascade is an evolutionarily conserved signal transduction pathway that regulates many vital cellular processes, including immune function and hematopoiesis. Human genetic variants that disrupt JAK-STAT signaling are being found to cause a rapidly increasing number of diseases, including both germline-encoded inborn errors of immunity (IEI) and acquired somatic variants, causing a so-called phenocopy of the IEI. Multiple genetic mechanisms are responsible for this growing group of JAK-STAT diseases including loss-of-function, gain-of-function, and dominant negative effects. In this review, we discuss the clinical presentation and pathogenesis of all currently described JAK-STAT defects, as well as provide an overview of the guiding principles to consider in diagnosing and treating these conditions.

DOCK8 deficiency due to a deep intronic variant in two kindreds with hyper-IgE syndrome.

Dedicator of cytokinesis 8 (DOCK8) deficiency underlies the majority of cases of patients with autosomal recessive form of the hyper-immunoglobulin E syndrome (HIES). Most DOCK8 mutations involve deletions and splice junction mutations that abrogate protein expression. However, a few patients whose presentation is reminiscent of DOCK8 deficiency have no identifiable mutations. Using Whole Exome Sequencing (WES), we identified a deep intronic homozygous DOCK8 variant located in intron 36 (c.4626 + 76 A > G) in two unrelated patients with features of HIES that resulted in an in-frame 75 base pair intronic sequence insertion in DOCK8 cDNA, resulting in a premature stop codon (p.S1542ins6Ter). This variant resulted in variable decrease in DOCK8 expression that was associated with impaired T cell receptor-triggered actin polymerization, decreased IL-6-induced STAT3 phosphorylation, reduced expression of the Th17 cell markers CCR6 and IL-17, and higher frequencies of GATA3+ T cells indicative of Th2 skewing. Our approach extends the reach of WES in identifying disease-related intronic variants. It highlights the role of non-coding mutations in immunodeficiency disorders, including DOCK8 deficiency, and emphasizes the need to explore these mutations in unexplained inborn errors of immunity.

Hypohidrotic ectodermal dysplasia caused by an intragenic duplication in EDAR.

Hypohidrotic Ectodermal Dysplasia is a syndrome with hypotrichosis, hypohidrosis, and hypodontia as the main symptoms. The prevalence is estimated to one in 5000-10,000 persons. In 10-15% the disease is caused by pathogenic variants in EDAR, and most of the known causal variants to date are missense or nonsense variants. We present a patient with classic Hypohidrotic Ectodermal Dysplasia and mammary gland aplasia with a duplication within EDAR as the likely cause. The duplication is de novo in the patient, and genome sequencing of DNA extracted from blood has revealed that the duplication is in tandem conformation, most likely entailing an altered EDAR protein with a dominant negative effect. This is to our knowledge the first report of an intragenic duplication in EDAR as causal for Hypohidrotic Ectodermal Dysplasia.

Clinical exome sequencing data from patients with inborn errors of immunity: Cohort level diagnostic yield and the benefit of systematic reanalysis.

While next generation sequencing has expanded the scientific understanding of Inborn Errors of Immunity (IEI), the clinical use and re-use of exome sequencing is still emerging. We revisited clinical exome data from 1300 IEI patients using an updated in silico IEI gene panel. Variants were classified and curated through expert review. The molecular diagnostic yield after standard exome analysis was 11.8 %. Through systematic reanalysis, we identified variants of interest in 5.2 % of undiagnosed patients, with 76.7 % being (candidate) disease-causing, providing a (candidate) diagnosis in 15.2 % of our cohort. We find a 1.7 percentage point increase in conclusive molecular diagnoses. We find a high degree of actionability in patients with a genetic diagnosis (76.4 %). Despite the modest absolute diagnostic gain, these data support the benefit of iterative exome reanalysis in IEI patients, conveying the notion that our current understanding of genes and variants involved in IEI is by far not saturated.