Publications by authors named "Janna Saarela"

87 Publications

Do monogenic inborn errors of immunity cause susceptibility to severe COVID-19?

J Clin Invest 2021 Jun 1. Epub 2021 Jun 1.

Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, United States of America.

The SARS-CoV-2 virus, which causes COVID-19, has been associated globally with substantial morbidity and mortality. Numerous reports over the past year have described the clinical and immunological profiles of COVID-19 patients, and while some trends have emerged for risk stratification, they do not provide a complete picture. Therefore, efforts are ongoing to identify genetic susceptibility factors of severe disease. In this issue of the JCI, Povysil et al. performed a large, multi-country study, sequencing genomes from patients with mild and severe COVID-19, along with population controls. Contrary to previous reports, the authors observed no enrichment of predicted loss-of-function variants in genes in the type I interferon pathway, which might predispose to severe disease. These studies suggest that more evidence is needed to substantiate the hypothesis for a genetic immune predisposition to severe COVID-19, and highlights the importance of considering experimental design when implicating a monogenic basis for severe disease.
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http://dx.doi.org/10.1172/JCI149459DOI Listing
June 2021

Loss of DIAPH1 causes SCBMS, combined immunodeficiency, and mitochondrial dysfunction.

J Allergy Clin Immunol 2021 Mar 1. Epub 2021 Mar 1.

PEDEGO Research Unit, University of Oulu, Oulu, Finland.

Background: Homozygous loss of DIAPH1 results in seizures, cortical blindness, and microcephaly syndrome (SCBMS). We studied 5 Finnish and 2 Omani patients with loss of DIAPH1 presenting with SCBMS, mitochondrial dysfunction, and immunodeficiency.

Objective: We sought to further characterize phenotypes and disease mechanisms associated with loss of DIAPH1.

Methods: Exome sequencing, genotyping and haplotype analysis, B- and T-cell phenotyping, in vitro lymphocyte stimulation assays, analyses of mitochondrial function, immunofluorescence staining for cytoskeletal proteins and mitochondria, and CRISPR-Cas9 DIAPH1 knockout in heathy donor PBMCs were used.

Results: Genetic analyses found all Finnish patients homozygous for a rare DIAPH1 splice-variant (NM_005219:c.684+1G>A) enriched in the Finnish population, and Omani patients homozygous for a previously described pathogenic DIAPH1 frameshift-variant (NM_005219:c.2769delT;p.F923fs). In addition to microcephaly, epilepsy, and cortical blindness characteristic to SCBMS, the patients presented with infection susceptibility due to defective lymphocyte maturation and 3 patients developed B-cell lymphoma. Patients' immunophenotype was characterized by poor lymphocyte activation and proliferation, defective B-cell maturation, and lack of naive T cells. CRISPR-Cas9 knockout of DIAPH1 in PBMCs from healthy donors replicated the T-cell activation defect. Patient-derived peripheral blood T cells exhibited impaired adhesion and inefficient microtubule-organizing center repositioning to the immunologic synapse. The clinical symptoms and laboratory tests also suggested mitochondrial dysfunction. Experiments with immortalized, patient-derived fibroblasts indicated that DIAPH1 affects the amount of complex IV of the mitochondrial respiratory chain.

Conclusions: Our data demonstrate that individuals with SCBMS can have combined immune deficiency and implicate defective cytoskeletal organization and mitochondrial dysfunction in SCBMS pathogenesis.
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http://dx.doi.org/10.1016/j.jaci.2020.12.656DOI Listing
March 2021

RhoG deficiency abrogates cytotoxicity of human lymphocytes and causes hemophagocytic lymphohistiocytosis.

Blood 2021 Apr;137(15):2033-2045

St Anna Children's Cancer Research Institute (CCRI), Vienna, Austria.

Exocytosis of cytotoxic granules (CG) by lymphocytes is required for the elimination of infected and malignant cells. Impairments in this process underly a group of diseases with dramatic hyperferritinemic inflammation termed hemophagocytic lymphohistiocytosis (HLH). Although genetic and functional studies of HLH have identified proteins controlling distinct steps of CG exocytosis, the molecular mechanisms that spatiotemporally coordinate CG release remain partially elusive. We studied a patient exhibiting characteristic clinical features of HLH associated with markedly impaired cytotoxic T lymphocyte (CTL) and natural killer (NK) cell exocytosis functions, who beared biallelic deleterious mutations in the gene encoding the small GTPase RhoG. Experimental ablation of RHOG in a model cell line and primary CTLs from healthy individuals uncovered a hitherto unappreciated role of RhoG in retaining CGs in the vicinity of the plasma membrane (PM), a fundamental prerequisite for CG exocytotic release. We discovered that RhoG engages in a protein-protein interaction with Munc13-4, an exocytosis protein essential for CG fusion with the PM. We show that this interaction is critical for docking of Munc13-4+ CGs to the PM and subsequent membrane fusion and release of CG content. Thus, our study illuminates RhoG as a novel essential regulator of human lymphocyte cytotoxicity and provides the molecular pathomechanism behind the identified here and previously unreported genetically determined form of HLH.
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http://dx.doi.org/10.1182/blood.2020008738DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8057258PMC
April 2021

Herpes simplex virus 2 encephalitis in a patient heterozygous for a TLR3 mutation.

Neurol Genet 2020 Dec 25;6(6):e532. Epub 2020 Nov 25.

Department of Internal Medicine (T.H., T.P.), Oulu University Hospital, Finland; Research Unit of Biomedicine (T.H., V.G., P.Å.), University of Oulu, Finland; St. Giles Laboratory of Human Genetics of Infectious Diseases (J.C., J.-L.C., S.-Y.Z.), Rockefeller Branch, The Rockefeller University, New York, NY; Department of Neurology (L.T., S.W.), Oulu University Hospital; Institute for Molecular Medicine Finland (J.L., J.S.), HiLIFE, and The Folkhälsan Research Center and Medicum (J.L.), University of Helsinki, Finland; Centre for Molecular Medicine Norway (J.S.), University of Oslo, Norway; Department of Clinical Genetics (M.K., O.K.), Oulu University Hospital, Finland; Department of Medical Microbiology (T.V.), Turku University Hospital and Institute of Biomedicine, University of Turku, Finland; Department of Clinical Neurophysiology (U.H.), Oulu University Hospital, Finland; Paris Descartes University (L.L., J.-L.C., S.-Y.Z.), Imagine Institute, Paris; Laboratory of Human Genetics of Infectious Diseases (J.-L.C., S.-Y.Z.), Necker Branch, INSERM UMR 1163, Necker Hospital for Sick Children, Paris; Pediatric Hematology-Immunology Unit (J.-L.C.), Necker Hospital for Sick Children, Paris, France; Howard Hughes Medical Institute (J.-L.C.), New York, NY; Adult Immunodeficiency Unit (M.R.J.S.), Infectious Diseases, Inflammation Center, University of Helsinki and HUS Helsinki University Hospital, Finland; and Rare Disease Center and Pediatric Research Center (M.R.J.S.), Children and Adolescents, University of Helsinki and HUS Helsinki University Hospital, Finland.

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http://dx.doi.org/10.1212/NXG.0000000000000532DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7720273PMC
December 2020

Somatic mutations and T-cell clonality in patients with immunodeficiency.

Haematologica 2020 12 1;105(12):2757-2768. Epub 2020 Dec 1.

Hematology Research Unit Helsinki, University of Helsinki, HUS, Helsinki, Finland.

Common variable immunodeficiency and other late-onset immunodeficiencies often co-manifest with autoimmunity and lymphoproliferation. The pathogenesis of most cases is elusive, as only a minor subset harbors known monogenic germline causes. The involvement of both B and T cells is however implicated. To study whether somatic mutations in CD4+ and CD8+ T cells associate with immunodeficiency, we recruited 17 patients and 21 healthy controls. Eight patients had late-onset common variable immunodeficiency and nine patients other immunodeficiency and/or severe autoimmunity. In total, autoimmunity occurred in 94% and lymphoproliferation in 65%. We performed deep sequencing of 2533 immune-associated genes from CD4+ and CD8+ cells. Deep T-cell receptor beta sequencing was used to characterize CD4+ and CD8+ T-cell receptor repertoires. The prevalence of somatic mutations was 65% in all immunodeficiency patients, 75% in common variable immunodeficiency and 48% in controls. Clonal hematopoiesis-associated variants in both CD4+ and CD8+ cells occurred in 24% of immunodeficiency patients. Results demonstrated mutations in known tumor suppressors, oncogenes, and genes that are critical for immune- and proliferative functions, such as STAT5B (two patients), C5AR1 (two patients), KRAS (one patient), and NOD2 (one patient). Additionally, as a marker of T-cell receptor repertoire perturbation, common variable immunodeficiency patients harbored increased frequencies of clones with identical complementarity determining region 3 sequences despite unique nucleotide sequences when compared to controls. In conclusion, somatic mutations in genes implicated for autoimmunity and lymphoproliferation are common in CD4+ and CD8+ cells of patients with immunodeficiency. They may contribute to immune dysregulation in a subset of immunodeficiency patients.
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http://dx.doi.org/10.3324/haematol.2019.220889DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7716374PMC
December 2020

Heterozygous TLR3 Mutation in Patients with Hantavirus Encephalitis.

J Clin Immunol 2020 11 16;40(8):1156-1162. Epub 2020 Sep 16.

Department of Internal Medicine, Oulu University Hospital, Oulu, Finland.

Puumala hantavirus (PUUV) hemorrhagic fever with renal syndrome (HFRS) is common in Northern Europe; this infection is usually self-limited and severe complications are uncommon. PUUV and other hantaviruses, however, can rarely cause encephalitis. The pathogenesis of these rare and severe events is unknown. In this study, we explored the possibility that genetic defects in innate anti-viral immunity, as analogous to Toll-like receptor 3 (TLR3) mutations seen in HSV-1 encephalitis, may explain PUUV encephalitis. We completed exome sequencing of seven adult patients with encephalitis or encephalomyelitis during acute PUUV infection. We found heterozygosity for the TLR3 p.L742F novel variant in two of the seven unrelated patients (29%, p = 0.0195). TLR3-deficient P2.1 fibrosarcoma cell line and SV40-immortalized fibroblasts (SV40-fibroblasts) from patient skin expressing mutant or wild-type TLR3 were tested functionally. The TLR3 p.L742F allele displayed low poly(I:C)-stimulated cytokine induction when expressed in P2.1 cells. SV40-fibroblasts from three healthy controls produced increasing levels of IFN-λ and IL-6 after 24 h of stimulation with increasing concentrations of poly(I:C), whereas the production of the cytokines was impaired in TLR3 L742F/WT patient SV40-fibroblasts. Heterozygous TLR3 mutation may underlie not only HSV-1 encephalitis but also PUUV hantavirus encephalitis. Such possibility should be further explored in encephalitis caused by these and other hantaviruses.
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http://dx.doi.org/10.1007/s10875-020-00834-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567724PMC
November 2020

Recessive MYH3 variants cause "Contractures, pterygia, and variable skeletal fusions syndrome 1B" mimicking Escobar variant multiple pterygium syndrome.

Am J Med Genet A 2020 11 9;182(11):2605-2610. Epub 2020 Sep 9.

Department of Clinical Genetics, HUSLAB, HUS Diagnostic Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

The multiple pterygium syndromes (MPS) are rare disorders with disease severity ranging from lethal to milder forms. The nonlethal Escobar variant MPS (EVMPS) is characterized by multiple pterygia and arthrogryposis, as well as various additional features including congenital anomalies. The genetic etiology of EVMPS is heterogeneous and the diagnosis has been based either on the detection of pathogenic CHRNG variants (~23% of patients), or suggestive clinical features. We describe four patients with a clinical suspicion of EVMPS who manifested with multiple pterygia, mild flexion contractures of several joints, and vertebral anomalies. We revealed recessively inherited MYH3 variants as the underlying cause in all patients: two novel variants, c.1053C>G, p.(Tyr351Ter) and c.3102+5G>C, as compound heterozygous with the hypomorphic MYH3 variant c.-9+1G>A. Recessive MYH3 variants have been previously associated with spondylocarpotarsal synostosis syndrome. Our findings now highlight multiple pterygia as an important feature in patients with recessive MYH3 variants. Based on all patients with recessive MYH3 variants reported up to date, we consider that this disease entity should be designated as "Contractures, pterygia, and variable skeletal fusions syndrome 1B," as recently suggested by OMIM. Our findings underline the importance of analyzing MYH3 in the differential diagnosis of EVMPS, particularly as the hypomorphic MYH3 variant might remain undetected by routine exome sequencing.
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http://dx.doi.org/10.1002/ajmg.a.61836DOI Listing
November 2020

Novel Hemizygous IL2RG p.(Pro58Ser) Mutation Impairs IL-2 Receptor Complex Expression on Lymphocytes Causing X-Linked Combined Immunodeficiency.

J Clin Immunol 2020 04 19;40(3):503-514. Epub 2020 Feb 19.

Translational Immunology Research Program, University of Helsinki, Helsinki, Finland.

Hypomorphic IL2RG mutations may lead to milder phenotypes than X-SCID, named variably as atypical X-SCID or X-CID. We report an 11-year-old boy with a novel c. 172C>T;p.(Pro58Ser) mutation in IL2RG, presenting with atypical X-SCID phenotype. We also review the growing number of hypomorphic IL2RG mutations causing atypical X-SCID. We studied the patient's clinical phenotype, B, T, NK, and dendritic cell phenotypes, IL2RG and CD25 cell surface expression, and IL-2 target gene expression, STAT tyrosine phosphorylation, PBMC proliferation, and blast formation in response to IL-2 stimulation, as well as protein-protein interactions of the mutated IL2RG by BioID proximity labeling. The patient suffered from recurrent upper and lower respiratory tract infections, bronchiectasis, and reactive arthritis. His total lymphocyte counts have remained normal despite skewed T and B cells subpopulations, with very low numbers of plasmacytoid dendritic cells. Surface expression of IL2RG was reduced on his lymphocytes. This led to impaired STAT tyrosine phosphorylation in response to IL-2 and IL-21, reduced expression of IL-2 target genes in patient CD4+ T cells, and reduced cell proliferation in response to IL-2 stimulation. BioID proximity labeling showed aberrant interactions between mutated IL2RG and ER/Golgi proteins causing mislocalization of the mutated IL2RG to the ER/Golgi interface. In conclusion, IL2RG p.(Pro58Ser) causes X-CID. Failure of IL2RG plasma membrane targeting may lead to atypical X-SCID. We further identified another carrier of this mutation from newborn SCID screening, lost to closer scrutiny.
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http://dx.doi.org/10.1007/s10875-020-00745-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142052PMC
April 2020

A Family With A20 Haploinsufficiency Presenting With Novel Clinical Manifestations and Challenges for Treatment.

J Clin Rheumatol 2020 Jan 21. Epub 2020 Jan 21.

Clinicum, Faculty of Medicine, University of Helsinki, Helsinki.

Background: Tumor necrosis factor α-induced protein 3 gene (TNFAIP3, also called A20) haploinsufficiency (HA20) leads to autoinflammation and autoimmunity. We have recently shown that a p.(Lys91*) mutation in A20 disrupts nuclear factor κB signaling, impairs protein-protein interactions of A20, and leads to inflammasome activation.

Methods: We now describe the clinical presentations and drug responses in a family with HA20 p.(Lys91*) mutation, consistent with our previously reported diverse immunological and functional findings.

Results: We report for the first time that inflammasome-mediated autoinflammatory lung reaction caused by HA20 can be treated with interleukin 1 antagonist anakinra. We also describe severe anemia related to HA20 successfully treated with mycophenolate. In addition, HA20 p.(Lys91*) was found to associate with autoimmune thyroid disease, juvenile idiopathic arthritis, psoriasis, liver disease, and immunodeficiency presenting with specific antibody deficiency and genital papillomatosis.

Conclusions: We conclude that HA20 may lead to combination of inflammation, immunodeficiency, and autoimmunity. The condition may present with variable and unpredictable symptoms with atypical treatment responses.
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http://dx.doi.org/10.1097/RHU.0000000000001268DOI Listing
January 2020

Phenotypic Variability with SLURP1 Mutations and Diffuse Palmoplantar Keratoderma.

Acta Derm Venereol 2020 Feb 25;100(4):adv00060. Epub 2020 Feb 25.

Department of Dermatology and Allergology, University of Helsinki and Helsinki University Central Hospital, 00029 HUS, Helsinki, Finland.

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http://dx.doi.org/10.2340/00015555-3404DOI Listing
February 2020

Novel TMEM173 Mutation and the Role of Disease Modifying Alleles.

Front Immunol 2019 5;10:2770. Epub 2019 Dec 5.

Institute of Biotechnology, University of Helsinki, Helsinki, Finland.

Upon binding to pathogen or self-derived cytosolic nucleic acids cyclic GMP-AMP synthase (cGAS) triggers the production of cGAMP that further activates transmembrane protein STING. Upon activation STING translocates from ER via Golgi to vesicles. Monogenic STING gain-of-function mutations cause early-onset type I interferonopathy, with disease presentation ranging from fatal vasculopathy to mild chilblain lupus. Molecular mechanisms underlying the variable phenotype-genotype correlation are presently unclear. Here, we report a novel gain-of-function G207E STING mutation causing a distinct phenotype with alopecia, photosensitivity, thyroid dysfunction, and features of STING-associated vasculopathy with onset in infancy (SAVI), such as livedo reticularis, skin vasculitis, nasal septum perforation, facial erythema, and bacterial infections. Polymorphism in and showed variable penetrance in the affected family, implying contribution to varying phenotype spectrum. The G207E mutation constitutively activates inflammation-related pathways , and causes aberrant interferon signature and inflammasome activation in patient PBMCs. Treatment with Janus kinase 1 and 2 (JAK1/2) inhibitor baricitinib was beneficiary for a vasculitic ulcer, induced hair regrowth and improved overall well-being in one patient. Protein-protein interactions propose impaired cellular trafficking of G207E mutant. These findings reveal the molecular landscape of STING and propose common polymorphisms in and as likely modifiers of the phenotype.
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http://dx.doi.org/10.3389/fimmu.2019.02770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6907089PMC
November 2020

Nagashima-type palmoplantar keratosis in Finland caused by a SERPINB7 founder mutation.

J Am Acad Dermatol 2020 Aug 7;83(2):643-645. Epub 2019 Nov 7.

Department of Dermatology, Skin and Allergy Hospital, University of Helsinki, ERN-skin, and Helsinki University Hospital, Helsinki, Finland.

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http://dx.doi.org/10.1016/j.jaad.2019.11.004DOI Listing
August 2020

A nearly fatal primary Epstein-Barr virus infection associated with low NK-cell counts in a patient receiving azathioprine: a case report and review of literature.

BMC Infect Dis 2019 May 10;19(1):404. Epub 2019 May 10.

Department of Children and Adolescents, Oulu University Hospital, P.O. Box 23, FIN-90029 OYS, Oulu, Finland.

Background: Symptomatic primary Epstein-Barr virus infection is a usually self-limiting illness in adolescents. We present a case of an adolescent who had been receiving azathioprine for inflammatory bowel disease for four years and developed a life-threatening primary Epstein-Barr virus infection successfully treated with rituximab.

Case Presentation: An 11-year-old girl presented with chronic, bloody diarrhea. Endoscopic biopsies confirmed a diagnosis of chronic ulcerative colitis with features of Crohn's disease. Azathioprine was initiated after one year due to active colitis. She responded well and remission was achieved. At the age of 16 years she developed a life-threatening Epstein-Barr virus infection including severe multiple organ failure and was critically ill for 4 weeks in the intensive care unit. Natural killer cells were virtually absent in the lymphocyte subset analysis. Azathioprine was stopped on admission. She was initially treated with corticosteroids, acyclovir and intravenous immunoglobulin. Approximately 30 days after admission, she developed signs of severe hepatitis and pneumonitis and received weekly rituximab infusions for 8 weeks. Primary immunodeficiency was excluded by whole exome sequencing in two independent laboratories. Persistent viremia stopped when the natural killer cell count started to rise, approximately 90 days after the cessation of azathioprine.

Conclusions: We found 17 comparable cases in the literature. None of the previous cases reported in the literature, who had been treated with azathioprine and developed either a severe or a fatal Epstein-Barr virus infection, underwent full genetic and prospective immunological workup to rule out known primary immunodeficiencies. Recently, azathioprine has been shown to cause rather specific immunosuppression, resulting in natural killer cell depletion. Our case demonstrates that slow recovery from azathioprine-induced natural killer cell depletion, 3 months after the stopping of azathioprine, coincided with the clearance of viremia and clinical recovery. Finally, our choice of treating the patient with rituximab, as previously used for patients with a severe immunosuppression and Epstein-Barr virus viremia, appeared to be successful in this case. We suggest testing for Epstein-Barr virus serology before starting azathioprine and measuring natural killer cell counts during the treatment to identify patients at risk of developing an unusually severe primary Epstein-Barr virus infection.
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http://dx.doi.org/10.1186/s12879-019-4022-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6509764PMC
May 2019

SLC18A3 variants lead to fetal akinesia deformation sequence early in pregnancy.

Am J Med Genet A 2019 07 6;179(7):1362-1365. Epub 2019 May 6.

Department of Clinical Genetics, HUSLAB, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

Fetal akinesia deformation sequence (FADS) and lethal multiple pterygium syndrome (LMPS) are clinically overlapping syndromes manifesting with reduced or absent fetal movement, arthrogryposis, and several anomalies during fetal life. The etiology of these syndromes is heterogeneous, and in many cases it remains unknown. In order to determine the genetic etiology of FADS in two fetuses with fetal akinesia, arthrogryposis, edema, and partial cleft palate, we utilized exome sequencing. Our investigations revealed a homozygous nonsense variant [c.1116C>A, p.(Cys372Ter)] in the SLC18A3 gene, which encodes for the vesicular acetylcholine transporter (VAChT) responsible for active transport of acetylcholine in the neuromuscular junction. This is the first description of a nonsense variant in the SLC18A3 gene, as only missense variants and whole gene deletions have been previously identified in patients. The previously detected SLC18A3 defects have been associated with congenital myasthenic syndromes, and therefore our findings extend the clinical spectrum of SLC18A3 defects to severe prenatal phenotypes. Our findings suggest that nonsense variants in SLC18A3 cause a more severe phenotype than missense variants and are in line with previous studies showing a lethal phenotype in VAChT knockout mice. Our results underline the importance of including SLC18A3 sequencing in the differential diagnostics of fetuses with arthrogryposis, FADS, or LMPS of unknown etiology.
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http://dx.doi.org/10.1002/ajmg.a.61186DOI Listing
July 2019

Genetic Association and Altered Gene Expression of in Multiple Sclerosis Patients.

Biomedicines 2018 Dec 18;6(4). Epub 2018 Dec 18.

Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090 Pieve Emanuele, Milan, Italy.

Multiple sclerosis (MS) is a chronic neurological disorder characterized by inflammation, demyelination, and axonal damage. Increased levels of reactive oxygen species (ROS), produced by macrophages and leading to oxidative stress, have been implicated as mediators of demyelination and axonal injury in both MS and experimental autoimmune encephalomyelitis, the murine model of the disease. On the other hand, reduced ROS levels can increase susceptibility to autoimmunity. In this work, we screened for association with MS 11 single nucleotide polymorphisms (SNPs) and two microsatellite markers in the five genes (, , , , and ) of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX2) system, the enzymatic pathway producing ROS in the brain and neural tissues, in 347 Finnish patients with MS and 714 unaffected family members. This analysis showed suggestive association signals for and (lowest = 0.038 and = 0.013, respectively). Functional relevance for disease predisposition was further supported for the gene, by microarray analysis in CD4 mononuclear cells of 21 individuals from five Finnish multiplex MS families, as well as by real-time RT-PCRs performed on RNA extracted from peripheral blood mononuclear cells of an Italian replication cohort of 21 MS cases and 21 controls. Our results showed a sex-specific differential expression of , suggesting that this gene, and more in general the NOX2 system, deserve to be further investigated for their possible role in MS.
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http://dx.doi.org/10.3390/biomedicines6040117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6315774PMC
December 2018

Haploinsufficiency of A20 impairs protein-protein interactome and leads into caspase-8-dependent enhancement of NLRP3 inflammasome activation.

RMD Open 2018 17;4(2):e000740. Epub 2018 Oct 17.

Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE), University of Helsinki, Helsinki, Finland.

Objectives: encodes A20 that negatively regulates nuclear factor kappa light chain enhancer of activated B cells (NF-κB), the major transcription factor coordinating inflammatory gene expression. polymorphisms have been linked with a spectrum of inflammatory and autoimmune diseases and, recently, loss-of-function mutations in A20 were found to cause a novel inflammatory disease 'haploinsufficiency of A20' (HA20). Here we describe a family with HA20 caused by a novel loss-of-function mutation and elucidate the upstream molecular mechanisms linking HA20 to dysregulation of NF-κB and the related inflammasome pathway.

Methods: NF-κB activation was studied in a mutation-expressing cell line using luciferase reporter assay. Physical and close-proximity protein-protein interactions of wild-type and p.(Lys91*) mutant A20 were analysed using mass spectrometry. NF-κB -dependent transcription, cytokine secretion and inflammasome activation were compared in immune cells of the HA20 patients and control subjects.

Results: The protein-protein interactome of p.(Lys91*) mutant A20 was severely impaired, including interactions with proteins regulating NF-κB activation, DNA repair responses and the NLR family pyrin domain containing 3 (NLRP3) inflammasome. The p.(Lys91*) mutant A20 failed to suppress NF-κB signalling, which led to increased NF-κB -dependent proinflammatory cytokine transcription. Functional experiments in the HA20 patients' immune cells uncovered a novel caspase-8-dependent mechanism of NLRP3 inflammasome hyperresponsiveness that mediated the excessive secretion of interleukin-1β and interleukin-18.

Conclusions: The current findings significantly deepen our understanding of the molecular mechanisms underlying HA20 and other diseases associated with reduced A20 expression or function, paving the way for future therapeutic targeting of the pathway.
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http://dx.doi.org/10.1136/rmdopen-2018-000740DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6203104PMC
October 2018

Diagnostics of rare disorders: whole-exome sequencing deciphering locus heterogeneity in telomere biology disorders.

Orphanet J Rare Dis 2018 08 17;13(1):139. Epub 2018 Aug 17.

Rare Disease Center, Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

Background: The telomere biology disorders (TBDs) include a range of multisystem diseases characterized by mucocutaneous symptoms and bone marrow failure. In dyskeratosis congenita (DKC), the clinical features of TBDs stem from the depletion of crucial stem cell populations in highly proliferative tissues, resulting from abnormal telomerase function. Due to the wide spectrum of clinical presentations and lack of a conclusive laboratory test it may be challenging to reach a clinical diagnosis, especially if patients lack the pathognomonic clinical features of TBDs.

Methods: Clinical sequencing was performed on a cohort of patients presenting with variable immune phenotypes lacking molecular diagnoses. Hypothesis-free whole-exome sequencing (WES) was selected in the absence of compelling diagnostic hints in patients with variable immunological and haematological conditions.

Results: In four patients belonging to three families, we have detected five novel variants in known TBD-causing genes (DKC1, TERT and RTEL1). In addition to the molecular findings, they all presented shortened blood cell telomeres. These findings are consistent with the displayed TBD phenotypes, addressing towards the molecular diagnosis and subsequent clinical follow-up of the patients.

Conclusions: Our results strongly support the utility of WES-based approaches for routine genetic diagnostics of TBD patients with heterogeneous or atypical clinical presentation who otherwise might remain undiagnosed.
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http://dx.doi.org/10.1186/s13023-018-0864-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6097299PMC
August 2018

Germline alterations in a consecutive series of acute myeloid leukemia.

Leukemia 2018 10 10;32(10):2282-2285. Epub 2018 Apr 10.

Genome-Scale Biology/Research Programs Unit, and Department of Medical and Clinical Genetics/Medicum, University of Helsinki, Helsinki, Finland.

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http://dx.doi.org/10.1038/s41375-018-0049-5DOI Listing
October 2018

ADA2 deficiency: Clonal lymphoproliferation in a subset of patients.

J Allergy Clin Immunol 2018 04 31;141(4):1534-1537.e8. Epub 2018 Jan 31.

Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland. Electronic address:

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http://dx.doi.org/10.1016/j.jaci.2018.01.012DOI Listing
April 2018

Who would benefit from exome sequencing?

Duodecim 2017;133(5):481-8

Next-generation sequencing methods have revolutionized the possibilities for analyzing the human genome. Sequencing the exome, the protein-encoding portion of the genome, is used, in clinical medicine, especially in the diagnosis of rare hereditary diseases, congenital developmental disorders and cancer. Using exome sequencing as a diagnostic test is justified when the results could lead to an accurate diagnosis, significantly influence the treatment and genetic counseling. It is a reliable method for detecting single base mutations as minor deletions and insertions. However, with current methods the reliable analysis of larger changes in the number of copies, the length or repeats and areas present in multiple copies in the genome is challenging. Every human has many mutations in their exome, and distinguishing between insignificant and pathogenic mutations is thus a key challenge when interpreting the results of exome sequencing.
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January 2018

Unexpectedly High Prevalence of Common Variable Immunodeficiency in Finland.

Front Immunol 2017 28;8:1190. Epub 2017 Sep 28.

Adult Immunodeficiency Unit, Infectious Diseases, Inflammation Center, University of Helsinki, Helsinki University Hospital, Helsinki, Finland.

Background: Common variable immunodeficiency (CVID) is the most common primary immunodeficiency. Prevalence varies greatly between countries and studies. Most diagnostic criteria include hypogammaglobulinemia and impaired vaccine response.

Aim: To evaluate the minimum prevalence as well as the clinical and immunological phenotypes of CVID in Southern Finland.

Methods: We performed a cross-sectional study to assess all adult CVID patients followed up in three hospital districts in Southern and South-Eastern Finland between April 2007 and August 2015. CVID diagnosis was based, with a minor modification, on the ESID/PAGID criteria for primary CVID. Antipolysaccharide responses to Pneumovax were defined as impaired only if 50% or more of the serotypes did not reach a level of 0.35 µg/mL after vaccination. We further characterized the patients' B cell phenotypes and complications associated with CVID.

Results: In total, 9 patients were excluded due to potential secondary causes before diagnosis. ESID/PAGID criteria were met by 132 patients (males 52%), of whom, 106 had "probable" and 26 "possible CVID." Based on the population statistics in the three hospital districts, the minimum adult prevalence per 100,000 inhabitants in Finland for all CVID ("probable CVID," respectively) patients was 6.9 (5.5). In the highest prevalence district (Helsinki and Uusimaa), the prevalence was 7.7 (6.1). CVID patients suffer from frequent complications. Ten patients died during follow-up. Of probable CVID patients, 73% had more than one clinical phenotype. Intriguingly, gradual B cell loss from peripheral blood during follow-up was seen in as many as 16% of "probable CVID" patients. Patients with possible CVID displayed somewhat milder clinical and laboratory phenotypes than probable CVID patients. We also confirm that large granular lymphocyte lymphoproliferation is a CVID-associated complication.

Conclusion: The prevalence of CVID in Finland appears the highest recorded, likely reflecting the genetic isolation and potential founder effects in the Finnish population. Studies to discover potential gene variants responsible for the high prevalence in Finland thus seem warranted. Increased awareness of CVID among physicians would likely lead to earlier diagnosis and improved quality of care.
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http://dx.doi.org/10.3389/fimmu.2017.01190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5625003PMC
September 2017

Hematopoietic stem cell transplantation rescues the hematological, immunological, and vascular phenotype in DADA2.

Blood 2017 12 3;130(24):2682-2688. Epub 2017 Oct 3.

Department of Pediatrics, Division of Immunology, University Hospitals of Leuven, Leuven, Belgium.

Deficiency of adenosine deaminase 2 (DADA2) is caused by biallelic deleterious mutations in DADA2 results in variable autoinflammation and vasculopathy (recurrent fevers, livedo reticularis, polyarteritis nodosa, lacunar ischemic strokes, and intracranial hemorrhages), immunodeficiency and bone marrow failure. Tumor necrosis factor-α blockade is the treatment of choice for the autoinflammation and vascular manifestations. Hematopoietic stem cell transplantation (HSCT) represents a potential definitive treatment. We present a cohort of 14 patients from 6 countries who received HSCT for DADA2. Indication for HSCT was bone marrow dysfunction or immunodeficiency. Six of 14 patients had vasculitis pre-HSCT. The median age at HSCT was 7.5 years. Conditioning regimens were myeloablative (9) and reduced intensity (5). Donors were HLA-matched sibling (n = 1), HLA-matched unrelated (n = 9), HLA-mismatched unrelated (n = 3), and HLA haploidentical sibling (n = 1). All patients are alive and well with no new vascular events and resolution of hematological and immunological phenotype at a median follow-up of 18 months (range, 5 months to 13 years). Plasma ADA2 enzyme activity normalized in those tested post-HSCT (7/7), as early as day +14 (myeloid engraftment). Post-HSCT hematological autoimmunity (cytopenias) was reported in 4 patients, acute graft-versus-host disease grade 1 in 2, grade 2 in 3, and grade 3-4 in 1, and moderate chronic graft-versus-host disease in 1 patient. In conclusion, in 14 patients, HSCT was an effective and definitive treatment of DADA2.
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http://dx.doi.org/10.1182/blood-2017-07-798660DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5731089PMC
December 2017

Damaging heterozygous mutations in NFKB1 lead to diverse immunologic phenotypes.

J Allergy Clin Immunol 2017 Sep 21;140(3):782-796. Epub 2017 Jan 21.

Adult Immunodeficiency Unit, Infectious Diseases, Inflammation Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland; Rare Diseases Center, Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

Background: The nuclear factor κ light-chain enhancer of activated B cells (NF-κB) signaling pathway is a key regulator of immune responses. Accordingly, mutations in several NF-κB pathway genes cause immunodeficiency.

Objective: We sought to identify the cause of disease in 3 unrelated Finnish kindreds with variable symptoms of immunodeficiency and autoinflammation.

Methods: We applied genetic linkage analysis and next-generation sequencing and functional analyses of NFKB1 and its mutated alleles.

Results: In all affected subjects we detected novel heterozygous variants in NFKB1, encoding for p50/p105. Symptoms in variant carriers differed depending on the mutation. Patients harboring a p.I553M variant presented with antibody deficiency, infection susceptibility, and multiorgan autoimmunity. Patients with a p.H67R substitution had antibody deficiency and experienced autoinflammatory episodes, including aphthae, gastrointestinal disease, febrile attacks, and small-vessel vasculitis characteristic of Behçet disease. Patients with a p.R157X stop-gain experienced hyperinflammatory responses to surgery and showed enhanced inflammasome activation. In functional analyses the p.R157X variant caused proteasome-dependent degradation of both the truncated and wild-type proteins, leading to a dramatic loss of p50/p105. The p.H67R variant reduced nuclear entry of p50 and showed decreased transcriptional activity in luciferase reporter assays. The p.I553M mutation in turn showed no change in p50 function but exhibited reduced p105 phosphorylation and stability. Affinity purification mass spectrometry also demonstrated that both missense variants led to altered protein-protein interactions.

Conclusion: Our findings broaden the scope of phenotypes caused by mutations in NFKB1 and suggest that a subset of autoinflammatory diseases, such as Behçet disease, can be caused by rare monogenic variants in genes of the NF-κB pathway.
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http://dx.doi.org/10.1016/j.jaci.2016.10.054DOI Listing
September 2017

Crowdsourced assessment of common genetic contribution to predicting anti-TNF treatment response in rheumatoid arthritis.

Nat Commun 2016 08 23;7:12460. Epub 2016 Aug 23.

MINES ParisTech, PSL-Research University, CBIO-Centre for Computational Biology, Fontainebleau 77300, France.

Rheumatoid arthritis (RA) affects millions world-wide. While anti-TNF treatment is widely used to reduce disease progression, treatment fails in ∼one-third of patients. No biomarker currently exists that identifies non-responders before treatment. A rigorous community-based assessment of the utility of SNP data for predicting anti-TNF treatment efficacy in RA patients was performed in the context of a DREAM Challenge (http://www.synapse.org/RA_Challenge). An open challenge framework enabled the comparative evaluation of predictions developed by 73 research groups using the most comprehensive available data and covering a wide range of state-of-the-art modelling methodologies. Despite a significant genetic heritability estimate of treatment non-response trait (h(2)=0.18, P value=0.02), no significant genetic contribution to prediction accuracy is observed. Results formally confirm the expectations of the rheumatology community that SNP information does not significantly improve predictive performance relative to standard clinical traits, thereby justifying a refocusing of future efforts on collection of other data.
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http://dx.doi.org/10.1038/ncomms12460DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4996969PMC
August 2016

Enrichment of rare variants in population isolates: single AICDA mutation responsible for hyper-IgM syndrome type 2 in Finland.

Eur J Hum Genet 2016 10 4;24(10):1473-8. Epub 2016 May 4.

Institute for Molecular Medicine Finland, University of Helsinki, Helsinki, Finland.

Antibody class-switch recombination and somatic hypermutation critically depend on the function of activation-induced cytidine deaminase (AID). Rare variants in its gene AICDA have been reported to cause autosomal recessive AID deficiency (autosomal recessive hyper-IgM syndrome type 2 (HIGM2)). Exome sequencing of a multicase Finnish family with an HIGM2 phenotype identified a rare, homozygous, variant (c.416T>C, p.(Met139Thr)) in the AICDA gene, found to be significantly enriched in the Finnish population compared with other populations of European origin (38.56-fold, P<0.001). The population history of Finland, characterized by a restricted number of founders, isolation and several population bottlenecks, has caused enrichment of certain rare disease-causing variants and losses of others, as part of a phenomenon called the Finnish Disease Heritage. Accordingly, rare founder mutations cause the majority of observed Finnish cases in these mostly autosomal recessive disorders that consequently are more frequent in Finland than elsewhere. Screening of all currently known Finnish patients with an HIGM2 phenotype showed them to be homozygous for p.(Met139Thr). All the Finnish p.(Met139Thr) carriers with available data on their geographic descent originated from the eastern and northeastern parts of Finland. They were observed to share more of their genome identity by descent (IBD) than Finns in general (P<0.001), and they all carried a 207.5-kb ancestral haplotype containing the variant. In conclusion, the identified p.(Met139Thr) variant is significantly enriched in Finns and explains all thus far found AID deficiencies in Finland.
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http://dx.doi.org/10.1038/ejhg.2016.37DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5027683PMC
October 2016

Constant B cell lymphocytosis since early age in a patient with CARD11 mutation: A 20-year follow-up.

Clin Immunol 2016 Apr 6;165:19-20. Epub 2016 Feb 6.

Tampere Center for Child Health Research, Tampere University and University Hospital, P.O. Box 2000, FI-33521 Tampere, Finland. Electronic address:

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http://dx.doi.org/10.1016/j.clim.2016.02.002DOI Listing
April 2016

Association study of MMP8 gene in osteoarthritis.

Connect Tissue Res 2016 17;57(1):44-52. Epub 2015 Nov 17.

p Department of Health Sciences , University of Jyväskylä, Jyväskylä , Finland.

Objectives: Osteoarthritis (OA) is a joint disease common in the elderly. There is a prior functional evidence for different matrix metalloproteinases (MMPs), such as MMP8 and MMP9, having a role in the breakdown of cartilage extracellular matrix in OA. Thus, we analyzed whether the common genetic variants of MMP8 and MMP9 contribute to the risk of OA.

Materials And Methods: In total, 13 common tagging single-nucleotide polymorphisms (SNPs) were studied in a discovery knee OA cohort of 185 cases and 895 controls. For validation, two knee OA replication cohorts and two hand OA replication cohorts were studied (altogether 1369 OA cases, 4445 controls in the five cohorts). The χ(2) test for individual study cohorts and Cochran-Mantel-Haenszel test for combined meta-analysis were calculated using Plink.

Results: The rs1940475 SNP in MMP8 showed suggestive association in the discovery cohort (OR = 0.721, 95% CI 0.575-0.906; p = 0.005). Other knee and hand OA replication study cohorts showed similar trend for the predisposing allele without reaching statistical significance in independent replication cohorts nor in their meta-analysis (p > 0.05). Meta-analysis of all five hand and knee OA study cohorts yielded a p-value of 0.027 (OR = 0.904, 95% CI 0.826-0.989).

Conclusions: Initial analysis of the MMP8 gene showed suggestive association between rs1940475 and knee OA, but the finding did not replicate in other study cohorts, even though the trend for predisposing allele was similar in all five cohorts. MMP-8 is a good biological candidate for OA, but our study did not find common variants with significant association in the gene.
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http://dx.doi.org/10.3109/03008207.2015.1099636DOI Listing
November 2016

Class II HLA interactions modulate genetic risk for multiple sclerosis.

Nat Genet 2015 Oct 7;47(10):1107-1113. Epub 2015 Sep 7.

Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.

Association studies have greatly refined the understanding of how variation within the human leukocyte antigen (HLA) genes influences risk of multiple sclerosis. However, the extent to which major effects are modulated by interactions is poorly characterized. We analyzed high-density SNP data on 17,465 cases and 30,385 controls from 11 cohorts of European ancestry, in combination with imputation of classical HLA alleles, to build a high-resolution map of HLA genetic risk and assess the evidence for interactions involving classical HLA alleles. Among new and previously identified class II risk alleles (HLA-DRB1*15:01, HLA-DRB1*13:03, HLA-DRB1*03:01, HLA-DRB1*08:01 and HLA-DQB1*03:02) and class I protective alleles (HLA-A*02:01, HLA-B*44:02, HLA-B*38:01 and HLA-B*55:01), we find evidence for two interactions involving pairs of class II alleles: HLA-DQA1*01:01-HLA-DRB1*15:01 and HLA-DQB1*03:01-HLA-DQB1*03:02. We find no evidence for interactions between classical HLA alleles and non-HLA risk-associated variants and estimate a minimal effect of polygenic epistasis in modulating major risk alleles.
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http://dx.doi.org/10.1038/ng.3395DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4874245PMC
October 2015

Stimulating translational research: several European life science institutions put their heads together.

Trends Mol Med 2015 Sep 5;21(9):525-7. Epub 2015 Aug 5.

EU-Life Translational Working Group; Centre for Genomic Regulation (CRG), Dr Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain.

Translational research leaves no-one indifferent and everyone expects a particular benefit. We as EU-LIFE (www.eu-life.eu), an alliance of 13 research institutes in European life sciences, would like to share our experience in an attempt to identify measures to promote translational research without undermining basic exploratory research and academic freedom.
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http://dx.doi.org/10.1016/j.molmed.2015.07.002DOI Listing
September 2015