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Öğe A Novel FOXN1 Variant Is Identified in Two Siblings with Nude Severe Combined Immunodeficiency(Springer/Plenum Publishers, 2019) Firtina, Sinem; Cipe, Funda; Ng, Yuk Yin; Kiykim, Ayca; Ng, Ozden Hatirnaz; Sudutan, Tugce; Aydogmus, Cigdem[Abstract Not Available]Öğe A novel pathogenic frameshift variant of CD3E gene in two T-B plus NK plus SCID patients from Turkey(Springer, 2017) Firtina, Sinem; Ng, Yuk Yin; Ng, Ozden Hatirnaz; Nepesov, Serdar; Yesilbas, Osman; Kilercik, Meltem; Burtecene, NihanSevere combined immunodeficiency (SCID) is the most severe form of primary immunodeficiency, which is characterized by the dysfunction and/or absence of T lymphocytes. Early diagnosis of SCID is crucial for overall survival, and if it remains untreated, SCID is often fatal. Next-generation sequencing (NGS) has become a rapid, high-throughput technology, and has already been proven to be beneficial in medical diagnostics. In this study, a targeted NGS panel was developed to identify the genetic variations of SCID by using SmartChip-TE technology, and a novel pathogenic frameshift variant was found in the CD3E gene. Sanger sequencing has confirmed the segregation of the variant among patients. We found a novel deletion in the CD3E gene (NM000733.3:p.L58Hfs*9) in two T-B+ NK+ patients. The variant was not found in the databases of dbSNP, ExAC, and 1000G. One sibling in family I was homozygous and the rest of the family members were heterozygous for this variant. T cell receptor excision circle (TREC) and kappa-deleting recombination excision circle (KREC) analyses were performed for T and B cell maturation. TRECs were not detected in both patients and the KREC copy numbers were similar to the other family members. In addition, heterozygous family members showed decreased TREC levels when compared with the wild-type sibling, indicating that carrying this variant in one allele does not cause immunodeficiency, but does effect T cell proliferation. Here, we report a novel pathogenic frameshift variant in CD3E gene by using targeted NGS panel.Öğe Determining T and B Cell development by TREC/KREC analysis in primary immunodeficiency patients and healthy controls(Wiley, 2022) Senturk, Gizem; Ng, Yuk Yin; Eltan, Sevgi Bilgic; Baser, Dilek; Ogulur, Ismail; Altindirek, Didem; Firtina, SinemT cell receptor excision circles (TRECs) and kappa-deleting excision circles (KRECs) are DNA fragments potentially indicative of T and B cell development, respectively. Recent thymic emigrants (RTEs) are a subset of peripheral cells that may also represent thymic function. Here, we investigated TREC/KREC copy numbers by quantitative real-time PCR in the peripheral blood of patients with primary immunodeficiencies (PIDs, n = 145) and that of healthy controls (HCs, n = 86) and assessed the correlation between RTEs and TREC copy numbers. We found that TREC copy numbers were significantly lower in children and adults with PIDs (P < .0001 and P < .002, respectively) as compared with their respective age-matched HCs. A moderate correlation was observed between TREC copies and RTE numbers among children with PID (r = .5114, P < .01), whereas no significant correlation was detected between RTE values and TREC content in the HCs (r = .0205, P = .9208). Additionally, we determined TREC and KREC copy numbers in DNA isolated from the Guthrie cards of 200 newborns and showed that this method is applicable to DNA isolated from both peripheral blood samples and dried blood spots, with the two sample types showing comparable TREC and KREC values. We further showed that RTE values are not always reliable markers of T cell output. Although additional confirmatory studies with larger cohorts are needed, our results provide thresholds for TREC/KREC copy numbers for different age groups.Öğe First Steps of the Genetic Monitorization in Primary Immune Deficiencies in the Lead of Prof. Dr. Isil Barlan in Turkey(Turkish Soc Immunology, 2015) Ng, Yuk Yin; Sisko, Sinem; Ng, Ozden Hatirnaz; Tatonyan, Suzin Catal; Kaya, Dilek Sever; Firtina, Sinem; Sayitoglu, Muge[Abstract Not Available]Öğe Identification of nonsense variants in the ATM gene mimicking SCID phenotype: a brief report(Springer, 2025) Firtina, Sinem; Saritas, Merve; Ng, Yuk Yin; Nepesov, Serdar; Kiykim, Ayca; Bozkurt, Selcen; Sayitoglu, MugeSevere combined immunodeficiency (SCID) represents a life-threatening inborn error of immunity, necessitating rapid diagnosis and intervention to prevent fatal outcomes. While SCID is characterized by profound T-cell lymphopenia, it may overlap with other conditions like ataxia-telangiectasia (AT), which also presents with T-cell deficiencies. This study examines two cases of suspected SCID in infants, later identified as AT due to pathogenic variants in the ATM gene. Despite initial negative results from SCID-targeted gene panels, further genetic testing revealed nonsense mutations (p.Y2036X and p.E1996X) in the FAT domain of the ATM gene, confirmed by Sanger sequencing. The patients exhibited significant T-cell lymphopenia and reduced ATM protein activity, indicative of AT. These findings highlight the importance of comprehensive genetic screening beyond common SCID-associated genes, especially in patients with atypical presentations. Early and accurate diagnosis can prevent mismanagement and guide appropriate therapies, improving patient outcomes.Öğe Mutational landscape of severe combined immunodeficiency patients from Turkey(Wiley, 2020) Firtina, Sinem; Ng, Yuk Yin; Ng, Ozden Hatirnaz; Kiykim, Ayca; Aydiner, Elif; Nepesov, Serdar; Camcioglu, YildizSevere combined immunodeficiency (SCID) has a diverse genetic aetiology, where a clinical phenotype, caused by single and/or multiple gene variants, can give rise to multiple presentations. The advent of next-generation sequencing (NGS) has recently enabled rapid identification of the molecular aetiology of SCID, which is crucial for prognosis and treatment strategies. We sought to identify the genetic aetiology of various phenotypes of SCIDs and assessed both clinical and immunologic characteristics associated with gene variants. An amplicon-based targeted NGS panel, which contained 18 most common SCID-related genes, was contumely made to screen the patients (n = 38) with typical SCID, atypical SCID or OMENN syndrome. Allelic segregations were confirmed for the detected gene variants within the families. In total, 24 disease-causing variants (17 known and 7 novel) were identified in 23 patients in 9 different SCID genes: RAG1 (n = 5), RAG2 (n = 2), ADA (n = 3), DCLRE1C (n = 2), NHEJ1 (n = 2), CD3E (n = 2), IL2RG (n = 3), JAK3 (n = 4) and IL7R (n = 1). The overall success rate of our custom-made NGS panel was 60% (39.3% for NK+ SCID and 100% for NK- SCID). Incidence of autosomal-recessive inherited genes is more frequently found in our cohort than the previously reported populations probably due to the high consanguineous marriages in Turkey. In conclusion, the custom-made sequencing panel was able to identify and confirm the previously known and novel disease-causing variants with high accuracy.Öğe Primary antibody deficiencies in Turkey: molecular and clinical aspects(Springer, 2022) Firtina, Sinem; Ng, Yuk Yin; Ng, Ozden H.; Kiykim, Ayca; Ozek, Esra Yucel; Kara, Manolya; Aydiner, ElifPrimary antibody deficiencies (PAD) are the most common subtype of primary immunodeficiencies, characterized by increased susceptibility to infections and autoimmunity, allergy, or malignancy predisposition. PAD syndromes comprise of immune system genes highlighted the key role of B cell activation, proliferation, migration, somatic hypermutation, or isotype switching have a wide spectrum from agammaglobulinemia to selective Ig deficiency. In this study, we describe the molecular and the clinical aspects of fifty-two PAD patients. The most common symptoms of our cohort were upper and lower respiratory infections, bronchiectasis, diarrhea, and recurrent fever. Almost all patients (98%) had at least one of the symptoms like autoimmunity, lymphoproliferation, allergy, or gastrointestinal disease. A custom-made next-generation sequencing (NGS) panel, which contains 24 genes, was designed to identify well-known disease-causing variants in our cohort. We identified eight variants (15.4%) among 52 PAD patients. The variants mapped to BTK (n = 4), CD40L (n = 1), ICOS (n = 1), IGHM (n = 1), and TCF3 (n = 1) genes. Three novel variants were described in the BTK (p.G414W), ICOS (p.G60*), and IGHM (p.S19*) genes. We performed Sanger sequencing to validate pathogenic variants and check for allelic segregation in the family. Targeted NGS panel sequencing can be beneficial as a suitable diagnostic modality for diagnosing well-known monogenic PAD diseases (only 2-10% of PADs); however, screening only the coding regions of the genome may not be adequately powered to solve the pathogenesis of PAD in all cases. Deciphering the regulatory regions of the genome and better understanding the epigenetic modifications will elucidate the molecular basis of complex PADs.Öğe TNFRSF13B VARIANTS ACT AS MODIFIERS TO CLINICAL PHENOTYPES IN COMMON VARIABLE IMMUNE DEFICIENCY DISORDERS(2023) Firtina, Sinem; Yenenler-kutlu, Aslı; Işıkgil, Begüm; Yozlu, Medinenur; Cepecı, Beyza Nur; Yilmaz, Hülya; Sayitoglu, Muge AydınObjective: The TNF receptor gene 13B (TNFSRF13B) is a member of the TNF superfamily which is crucial for B cell maturation, plasma cell differentiation, and antibody response. Impaired expression of the TNFRSF13B gene is associated with common variable immune deficiency (CVID), autoimmunity, and lymphoproliferation disorders. Besides the disease-causing variants of this gene, its different isoforms are associated with strong and weak TNFRSF13B expression that leads to an unbalanced B cell response. Materials and Methods: The study detected 26 variants (three synonymous, five missenses, eleven UTR, and seven intronic variants) in the TNFRSF13B gene by screening 68 CVID patients with targeted next generation sequencing. An integrative bioinformatics approach was utilized to provide a plausible explanation for CVID associations from different perspectives and to investigate the associations from the clinical findings. Results: Fifty-eight percent (15/26) of the detected variants were altered regulatory elements, such as transcription factor binding, miRNA binding sites, splice site regions or the thermodynamic impact on protein. We observed that patients who suffered from the potential splicing variants had significantly low IgA levels (p=0.009), autoimmunity (p=0.02) and gastrointestinal findings (p=0.05). In addition, the c.*79A>G 3-UTR variant was found with the low IgA and IgE levels. Thirteen variants found to have at least tenfold increased allele frequencies as compared to global databases indicating that the TNFRSF13B variants, which have a potential regulatory effect, are more common in CVID patients. Conclusions: All findings suggested that these variants may not be the causative variant for the CVID phenotype but the unbalanced TNFRSF13B alternative splices could contribute to the pathogenesis of patients independent from the underlying genetic background of CVID.
