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Bloom Syndrome (BS) is a genetic DNA repair disorder, caused by mutations in the BLM gene. The clinical phenotype includes growth retardation, immunodeficiency and a strong predisposition to different types of malignancies. Treatment of malignancies in BS patients with radiotherapy or chemotherapy is believed to be associated with increased toxicity, but clinical and laboratory data are lacking. We collected clinical data of two Dutch BS patients with solid tumors. Both were treated with radiotherapy before the diagnosis BS was made and tolerated this treatment well. In addition, we collected fibroblasts from BS patients to perform in vitro clonogenic survival assays to determine radiosensitivity. BS fibroblasts showed less radiosensitivity than the severely radiosensitive Artemis fibroblasts. Moreover, studies of double strand break kinetics by counting 53BP1 foci after irradiation showed similar patterns compared to healthy controls. In combination, the clinical cases and laboratory experiments are valuable information in the discussion whether radiotherapy is absolutely contraindicated in BS, which is the Case in other DNA repair syndromes like Ataxia Telangiectasia and Artemis.

Ataxia Telangiectasia (AT) is a rare inherited disorder characterized by progressive cerebellar ataxia, chromosomal instability, cancer susceptibility and immunodeficiency. AT is caused by mutations in the ATM gene, which is involved in multiple processes linked to DNA double strand break repair. Immunologically, ATM mutations lead to hampered V(D)J recombination and consequently reduced numbers of naive B and T cells. In addition, class switch recombination is disturbed resulting in antibody deficiency causing common, mostly sinopulmonary, bacterial infections. Yet, AT patients in general have no clinical T cell associated infections and numbers of memory T cells are usually normal. In this study we investigated the naive and memory T cell compartment in five patients with classical AT and compared them with five healthy controls using a 24-color antibody panel and spectral flow cytometry. Multidimensional analysis of CD4 and CD8 TCRαβ+ cells revealed that early naive T cell populations, i.e. CD4+CD31+ recent thymic emigrants and CD8+CCR7++CD45RA++ T cells, were strongly reduced in AT patients. However, we identified normal numbers of stem cell memory T cells expressing CD95, which are antigen-experienced T cells that can persist for decades because of their self-renewal capacity. We hypothesize that the presence of stem cell memory T cells explains why AT patients have an intact memory T cell compartment. In line with this novel finding, memory T cells of AT patients were normal in number and expressed chemokine receptors, activating and inhibitory receptors in comparable percentages as controls. Comparing memory T cell phenotypes by Boolean gating revealed similar diversity indices in AT compared to controls. We conclude that AT patients have a fully developed memory T cell compartment despite strongly reduced naive T cells. This could be explained by the presence of normal numbers of stem cell memory T cells in the naive T cell compartment, which support the maintenance of the memory T cells. The identification of stem cell memory T cells via our spectral flow cytometric approach is highly relevant for better understanding of T cell immunity in AT. Moreover, it provides possibilities for further research on this recently identified T cell population in other inborn errors of immunity.

Background: We aimed to expand the number of currently known pathogenic PNKP mutations, to study the phenotypic spectrum, including radiological characteristics and genotype-phenotype correlations, and to assess whether immunodeficiency and increased cancer risk are part of the DNA repair disorder caused by mutations in the PNKP gene.Methods: We evaluated nine patients with PNKP mutations. A neurological history and examination was obtained. All patients had undergone neuroimaging and genetic testing as part of the prior diagnostic process. Laboratory measurements included potential biomarkers, and, in the context of a DNA repair disorder, we performed a detailed immunologic evaluation, including B cell repertoire analysis.Results: We identified three new mutations in the PNKP gene and confirm the phenotypic spectrum of PNKP-associated disease, ranging from microcephaly, seizures, and developmental delay to ataxia with oculomotor apraxia type 4. Irrespective of the phenotype, alpha-fetoprotein is a biochemical marker and increases with age and progression of the disease. On neuroimaging, (progressive) cerebellar atrophy was a universal feature. No clinical signs of immunodeficiency were present, and immunologic assessment was unremarkable. One patient developed cancer, but this was attributed to a concurrent von Hippel-Lindau mutation.Conclusions: Immunodeficiency and cancer predisposition do not appear to be part of PNKP-associated disease, contrasting many other DNA repair disorders. Furthermore, our study illustrates that the previously described syndromes microcephaly, seizures, and developmental delay, and ataxia with oculomotor apraxia type 4, represent the extremes of an overlapping spectrum of disease. Cerebellar atrophy and elevated serum alpha-fetoprotein levels are early diagnostic findings across the entire phenotypical spectrum. (C) 2020 The Author(s). Published by Elsevier Inc.

Antibody replacement therapy for patients with antibody deficiencies contains only IgG. As a result, concurrent IgM and IgA deficiency present in a large proportion of antibody deficient patients persists. Especially patients with IgM deficiency remain at risk for recurrent infections of the gastrointestinal and respiratory tract. The lack of IgM in the current IgG replacement therapy is likely to contribute to the persistence of these mucosal infections because this antibody class is especially important for complement activation on the mucosal surface. We evaluated whether supplementation with IgM increased serum bactericidal capacity in vitro. Serum was collected from a patient with agammaglobulinemia and supplemented with purified serum IgM to normal levels. Antibody and complement deposition on the bacterial surface was determined by multi-color flow cytometry. Bacterial survival in serum was determined by colony-forming unit counts. We present a patient previously diagnosed with agammaglobulinemia due to CD79A (Igα) deficiency revealing a novel pathogenic insertion variant in the CD79a gene (NM_001783.3:c.353_354insT). Despite IgG replacement therapy and antibiotic prophylaxis, this patient developed a Campylobacter jejuni spondylodiscitis of lumbar vertebrae L4–L5. We found that serum IgM significantly contributes to complement activation on the bacterial surface of C. jejuni. Furthermore, supplementation of serum IgM augmented serum bactericidal activity significantly. In conclusion, supplementation of intravenous IgG replacement therapy with IgM may potentially offer greater protection against bacterial infections, also in the context of increasing antibiotic resistance.

Ataxia telangiectasia (A-T) is a severe neurodegenerative disorder with variable immunodeficiency. Together with the Dutch A-T community, we investigated the opinion of A-T parents on an early A-T diagnosis in the asymptomatic phase of the disease. During an annual national meeting for A-T patients and families, the topic of an early A-T diagnosis was discussed in relation to the recent introduction of neonatal screening for severe combined immunodeficiency (SCID) in the Netherlands. Based on the discussion, individual arguments were identified and processed into a questionnaire, which was sent out to 64 A-T parents (32 families). Arguments included were insecurity to diagnosis, possible medical advantages, appropriate genetic counseling and family planning, loss of “golden” year(s), and early cancer screening for parents. The response rate was 55% (n = 35 parents). Twenty-six (74%) parents felt that the advantages of an early diagnosis outweighed the disadvantages, five parents thought that the disadvantages would outweigh the advantages (14%), and four parents did not indicate a preference. Conclusion: The majority of parents of a child with A-T would have preferred an early diagnosis during the asymptomatic phase of the disease, because the uncertainty during the diagnostic process had had a major impact on their lives. In addition, the knowledge of being carriers of an ATM gene mutation influenced decisions about family planning. Parents who opposed against an early diagnosis emphasized the joy of having a seemingly healthy child until diagnosis.What is Known:• Ataxia telangiectasia (A-T) is a devastating DNA repair disorder with a huge impact on quality of life of patients and their parents.• Patients with A-T may incidentally be identified at birth as the consequence of neonatal screening for severe combined immunodeficiency (SCID).What is New:• The majority of Dutch parents of A-T patients (74%) would have preferred an early diagnosis of their child in the asymptomatic phase of the disease.• Major arguments for an early A-T diagnosis were (1) the experienced insecurity in diagnostic trajectories and its impact on families and (2) the knowledge of being ATM mutation carriers when deciding about family planning. An argument against an early diagnosis is losing the joy of having a seemingly healthy child until diagnosis.

Item does not contain fulltext Patient registries are instrumental for clinical research in rare diseases. They help to achieve a sufficient sample size for epidemiological and clinical research and to assess the feasibility of clinical trials. The European Society for Immunodeficiencies (ESID) registry currently comprises information on more than 25,000 patients with inborn errors of immunity (IEI). The prerequisite of a patient to be included into the ESID registry is an IEI either defined by a defect in a gene included in the disease classification of the international union of immunological societies, or verified by applying clinical criteria. Because a relevant number of patients, including those with common variable immunodeficiency (CVID), representing the largest group of patients in the registry, remain without a genetic diagnosis, consensus on classification of these patients is mandatory. Here, we present clinical criteria for a large number of IEI that were designed in expert panels with an external review. They were implemented for novel entries and verification of existing data sets from 2014, yielding a substantial refinement. For instance, 8% of adults and 27% of children with CVID (176 of 1704 patients) were reclassified to 22 different immunodeficiencies, illustrating progress in genetics, but also the previous lack of standardized disease definitions. Importantly, apart from registry purposes, the clinical criteria are also helpful to support treatment decisions in the absence of a genetic diagnosis or in patients with variants of unknown significance.

Contains fulltext : 137474.pdf (Publisher’s version ) (Closed access) Alpha-fetoprotein (AFP) is present in fetal serum in concentrations up to 5,000,000 mug/l. After birth, AFP gene expression is turned down with a subsequent fall of the serum concentrations of this albumin-like protein to 'adult values' of circa 0.5-15 mug/l from the age of 2 years onwards. Irrespective of its assumed important functions, individuals with AFP deficiency appear fully healthy. The other way around, the presence of AFP in the circulation after the first years of life doesn't seem to harm, since individuals with 'hereditary persistence of AFP' are also without clinical abnormalities. During pregnancy, AFP (in maternal serum) has long been recognized as a marker for congenital anomalies of the fetus. Equally well known is AFP as biomarker for hepatocellular carcinoma and some other malignancies. There are at least four neurodegenerative disorders, all inherited as autosomal recessive traits and characterized by the presence of cerebellar ataxia, abnormal ocular movements, and neuropathy, for which an elevated concentration of serum AFP is an important diagnostic biomarker. The availability of a reliable biomarker is not only important during screening or diagnostic processes, but is also relevant for objective follow-up during (future) therapeutic interventions.

Nature Communications 6: Article number: 7870 (2015); Published: 28 July 2015; Updated: 22 June 2016 In Fig. 1b of this Article, the sex of patient 2.1 in family A is incorrect, and should be depicted as male. The correct version of this figure appears below. Figure 1

Artemis deficiency is known to result in classical T-B- severe combined immunodeficiency (SCID) in case of Artemis null mutations, or Omenn's syndrome in case of hypomorphic mutations in the Artemis gene. We describe two unrelated patients with a relatively mild clinical T-B- SCID phenotype, caused by different homozygous Artemis splice-site mutations. The splice-site mutations concern either dysfunction of a 5' splice-site or an intronic point mutation creating a novel 3' splice-site, resulting in mutated Artemis protein with residual activity or low levels of wild type (WT) Artemis transcripts. During the first 10 years of life, the patients suffered from recurrent infections necessitating antibiotic prophylaxis and intravenous immunoglobulins. Both mutations resulted in increased ionizing radiation sensitivity and insufficient variable, diversity and joining (V(D)J) recombination, causing B-lymphopenia and exhaustion of the naive T-cell compartment. The patient with the novel 30 splice-site had progressive granulomatous skin lesions, which disappeared after stem cell transplantation (SCT). We showed that an alternative approach to SCT can, in principle, be used in this case; an antisense oligonucleotide (AON) covering the intronic mutation restored WT Artemis transcript levels and non-homologous end-joining pathway activity in the patient fibroblasts. Genes and Immunity (2011) 12, 434-444; doi:10.1038/gene.2011.16; published online 10 March 2011

The Immunodeficiency, Centromeric region instability, Facial anomalies syndrome (ICF) is a rare autosomal recessive disease described in about 50 patients worldwide and characterized by immunodeficiency, although B cells are present, and by characteristic rearrangements in the vicinity of the centromeres (the juxtacentromeric heterochromatin) of chromosomes 1 and 16 and sometimes 9. Other variable symptoms of this probably under-diagnosed syndrome include mild facial dysmorphism, growth retardation, failure to thrive, and psychomotor retardation. Serum levels of IgG, IgM, IgE, and/or IgA are low, although the type of immunoglobulin deficiency is variable. Recurrent infections are the presenting symptom, usually in early childhood. ICF always involves limited hypomethylation of DNA and often arises from mutations in one of the DNA methyltransferase genes (DNMT3B). Much of this DNA hypomethylation is in 1qh, 9qh, and 16qh, regions that are the site of whole-arm deletions, chromatid and chromosome breaks, stretching (decondensation), and multiradial chromosome junctions in mitogen-stimulated lymphocytes. By an unknown mechanism, the DNMT3B deficiency that causes ICF interferes with lymphogenesis (at a step after class switching) or lymphocyte activation. With the identification of DNMT3B as the affected gene in a majority of ICF patients, prenatal diagnosis of ICF is possible. However, given the variety of DNMT3B mutations, a first-degree affected relative should first have both alleles of this gene sequenced. Treatment almost always includes regular infusions of immunoglobulins, mostly intravenously. Recently, bone marrow transplantation has been tried.

Immunological disturbances may result in altered immunoglobulin concentrations and kappa/lambda light chain (kappa/lambda) ratios. We measured the kappa/lambda ratios of total serum immunoglobulins and of polyclonal IgG, A, and M separately as well as concentrations of these immunoglobulins in fourteen patients with juvenile onset mixed connective tissue disease. When comparing the patient group with a reference group the mean serum IgG and IgA concentrations were respectively 2.98 G/L (p = 0.0012) and 0.79 G/L (p = 0.0114) higher in the group of patients with juvenile onset mixed connective tissue disease. The mean IgM concentration was 0.39 G/L (p = 0.0002) lower. The mean kappa/lambda ratios of total serum immunoglobulins, serum IgG, and serum IgA were respectively 0.20 (p = 0.0226), 0.28 (p = 0.0016) and 0.10 (p = 0.0732), higher in the group of patients with mixed connective tissue disease as compared with the reference group. Mean serum IgM kappa/lambda ratio, however, was 0.21 (p = 0.0046) lower. The alterations of the serum immunoglobulin concentrations and of the kappa/lambda ratios reflect immunological disturbances in patients with juvenile onset mixed connective tissue disease. The increased concentration of serum IgG and raised IgG kappa/lambda ratio and decreased concentration of serum IgM with decreased IgM kappa/lambda ratio indicate that the synthesis of kappa-bearing immunoglobulins mainly is affected.