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ÖZEN, AHMET OĞUZHAN

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ÖZEN

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AHMET OĞUZHAN

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2016 - 201922020 - 20211
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Author: ÖĞÜLÜR, İSMAİL × Subject: DEFICIENCY ×

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    PublicationOpen Access
    Severe Early-Onset Combined Immunodeficiency due to Heterozygous Gain-of-Function Mutations in STAT1
    (SPRINGER/PLENUM PUBLISHERS, 2016-10) ÖZEN, AHMET OĞUZHAN; Baris, Safa; Alroqi, Fayhan; Kiykim, Ayca; Karakoc-Aydiner, Elif; Ogulur, Ismail; Ozen, Ahmet; Charbonnier, Louis-Marie; Bakir, Mustafa; Boztug, Kaan; Chatila, Talal A.; Barlan, Isil B.
    Loss and gain-of-function (GOF) mutations in human signal transducer and activator of transcription 1 (STAT1) lead to distinct phenotypes. Although recurrent infections are common to both types of STAT1 mutations, GOF mutations are distinguished by chronic mucocutaneous candidiasis and autoimmunity. However, the clinical spectra of STAT1 GOF mutations continue to expand. We here describe two patients with STAT1 GOF mutations presenting early in life with combined immunodeficiency (CID). Clinical data and laboratory findings including immunophenotyping, level of interferon (IFN)-gamma/IL-17(+) T cells, interferon-induced STAT1 phosphorylation, and JAK inhibitor assays were evaluated. Sequencing of STAT1 gene was performed by Sanger sequencer. Patient 1 (P1) had persistent oral candidiasis and cytomegalovirus (CMV) infection since 2 months of age and later developed cavitary lung lesions due to Mycobacterium tuberculosis. Patient 2 (P2) presented with oral candidiasis and recurrent pneumonia at 4 months of age and subsequently developed CMV pneumonitis. Both patients suffered heterozygous missense mutations in STAT1, leading to deleterious amino acid substitutions in the DNA binding domain (P1: c.1154C > T; p.T385M; P2. c.971G > T; p.C324F). Circulating CD4(+) T cells of both patients exhibited increased interferon-gamma and decreased IL-17 expression as compared to controls. They also exhibited increased IFN-beta and -gamma-induced STAT1 phosphorylation that was reversed upon treatment with the JAK kinase inhibitor ruxolitinib. STAT1 GOF mutations may present early in life with CID, consistent with the clinical heterogeneity of the disease. JAK kinase inhibitors may potentially be useful in some patients as adjunct therapy pending definitive treatment with bone marrow transplantation.
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    Parents of ataxia-telangiectasia patients display a distinct cellular immune phenotype mimickingATM-mutated patients
    (WILEY, 2021) ÖZEN, AHMET OĞUZHAN; Ogulur, Ismail; Ertuzun, Tugce; Kocamis, Burcu; Kendir Demirkol, Yasemin; Uyar, Emel; Kiykim, Ayca; Baser, Dilek; Yesil, Gozde; Akturk, Hacer; Somer, Ayper; Ozen, Ahmet; Karakoc-Aydiner, Elif; Muftuoglu, Meltem; Baris, Safa
    Background Heterozygous relatives of ataxia-telangiectasia (AT) patients are at an increased risk for certain AT-related manifestations. We also show that there is an increase of infection frequency in parents of AT patients. Thus, we hypothesized that the parents might exhibit immune alterations similar to their affected children. Methods Lymphocyte phenotyping to enumerate T- and B-cell subsets was performed. Functional analyses included in vitro quantified gamma-H2AX, poly (ADP-ribose) polymerase (PARP) and caspase-9 proteins. Chromosomal instability was determined by comet assay. Results We analyzed 20 AT patients (14F/6M), 31 parents (16F/15M), and 35 age-matched healthy controls. The AT patients' parents exhibited low frequency of naive CD4(+)T- (n = 14, 45%) and recent thymic emigrants (n = 11, 35%) in comparison with the age-matched healthy donors. Interestingly, parents with low naive T cells also demonstrated high rate of recurrent infections (9/14, 64%). In comparison with age-matched controls, parents who had recurrent infections and low naive T cells showed significantly higher baseline gamma-H2AX levels and H2O2-induced DNA damage as well as increased cleaved caspase-9 and PARP proteins. Conclusion Parents of AT patients could present with recurrent infections and display cellular defects that mimic AT patients. The observed immunological changes could be associated with increased DNA double-strand breaks.
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    PublicationOpen Access
    Immune system defects in DiGeorge syndrome and association with clinical course
    (WILEY, 2019-11) ÖZEN, AHMET OĞUZHAN; Nain, Ercan; Kiykim, Ayca; Ogulur, Ismail; Kasap, Nurhan; Karakoc-Aydiner, Elif; Ozen, Ahmet; Baris, Safa
    We evaluated 18 DiGeorge syndrome (DGS) patients and aimed to investigate the immunological changes in this population. DGS patients with low naive CD4(+)T and CD8(+)T cells were defined as high-risk (HR) patients, whereas patients with normal numbers of naive CD4(+) and CD8(+)T cells were defined as standard risk (SR) patients. Level of serum IgM, CD3(+) T cell counts and percentages of class-switched memory B cells were significantly low in HR group compared to SR ones. Severe infections and persistent hypoparathyroidism were detected significantly higher in HR group. Patients with reduced percentages of class-switched B cells had earlier onset of infection, lower blood IgM, lower CD4(+) and CD8(+)T counts than patients with normal class-switched memory B cells. Decreased levels of IgM were associated with low numbers of naive CD4(+) and recent thymic emigrants T cells. Monitoring the immune changes of patients with DGS would be useful to predict the severe phenotype of disease.