Turkan Patiroglu

Hypomorphic homozygous mutations in phosphoglucomutase 3 (PGM3) impair immunity and increase serum IgE levels

BACKGROUND Recurrent bacterial and fungal infections, eczema, and increased serum IgE levels characterize patients with the hyper-IgE syndrome (HIES). Known genetic causes for HIES are mutations in signal transducer and activator of transcription 3 (STAT3) and dedicator of cytokinesis 8 (DOCK8), which are involved in signal transduction pathways. However, glycosylation defects have not been described in patients with HIES. One crucial enzyme in the glycosylation pathway is phosphoglucomutase 3 (PGM3), which catalyzes a key step in the synthesis of uridine diphosphate N-acetylglucosamine, which is required for the biosynthesis of N-glycans. OBJECTIVE We sought to elucidate the genetic cause in patients with HIES who do not carry mutations in STAT3 or DOCK8. METHODS After establishing a linkage interval by means of SNPchip genotyping and homozygosity mapping in 2 families with HIES from Tunisia, mutational analysis was performed with selector-based, high-throughput sequencing. Protein expression was analyzed by means of Western blotting, and glycosylation was profiled by using mass spectrometry. RESULTS Mutational analysis of candidate genes in an 11.9-Mb linkage region on chromosome 6 shared by 2 multiplex families identified 2 homozygous mutations in PGM3 that segregated with disease status and followed recessive inheritance. The mutations predict amino acid changes in PGM3 (p.Glu340del and p.Leu83Ser). A third homozygous mutation (p.Asp502Tyr) and the p.Leu83Ser variant were identified in 2 other affected families, respectively. These hypomorphic mutations have an effect on the biosynthetic reactions involving uridine diphosphate N-acetylglucosamine. Glycomic analysis revealed an aberrant glycosylation pattern in leukocytes demonstrated by a reduced level of tri-antennary and tetra-antennary N-glycans. T-cell proliferation and differentiation were impaired in patients. Most patients had developmental delay, and many had psychomotor retardation. CONCLUSION Impairment of PGM3 function leads to a novel primary (inborn) error of development and immunity because biallelic hypomorphic mutations are associated with impaired glycosylation and a hyper-IgE-like phenotype.

Clinical, functional, and genetic characterization of chronic granulomatous disease in 89 Turkish patients

BACKGROUND Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disorder of phagocytes resulting in impaired killing of bacteria and fungi. A mutation in one of the 4 genes encoding the components p22(phox), p47(phox), p67(phox), and p40(phox) of the leukocyte nicotinamide dinucleotide phosphate reduced (NADPH) oxidase leads to autosomal recessive (AR) CGD. A mutation in the CYBB gene encoding gp91(phox) leads to X-linked recessive CGD. OBJECTIVE The aim of this study is to show the correlation between clinical, functional, and genetic data of patients with CGD from Turkey. METHODS We report here the results of 89 patients with CGD from 73 Turkish families in a multicenter study. RESULTS Most of the families (55%) have an AR genotype, and 38% have an X-linked genotype; patients from 5 families with a suspected AR genotype (7%) were not fully characterized. We compared patients with CGD according to the severity of NADPH oxidase deficiency of neutrophils. Patients with A22(0), A67(0) or X91(0) phenotypes with a stimulation index of 1.5 or less have early clinical presentation and younger age at diagnosis (mean, 3.2 years). However, in p47(phox)-deficient cases and in 5 other AR cases with high residual oxidase activity (stimulation index ≥ 3), later and less severe clinical presentation and older age at diagnosis (mean, 7.1 years) were found. Pulmonary involvement was the most common clinical feature, followed by lymphadenitis and abscesses. CONCLUSION Later and less severe clinical presentation and older age at diagnosis are related to the residual NADPH oxidase activity of neutrophils and not to the mode of inheritance. CGD caused by A22(0) and A67(0) subtypes manifests as severe as the X91(0) subtype.

Genetic, immunological, and clinical features of patients with bacterial and fungal infections due to inherited IL-17RA deficiency

Significance Chronic mucocutaneous candidiasis (CMC) is defined as persistent or recurrent infections of the skin and/or mucosae by commensal fungi of the Candida genus. It is often seen in patients with T-cell deficiencies, whether inherited or acquired, who typically suffer from multiple infectious diseases. Rare patients are otherwise healthy and display isolated CMC, which often segregates as a Mendelian trait. In 2011, we described the first genetic cause of isolated CMC, with autosomal recessive (AR), complete IL-17 receptor A (IL-17RA) deficiency, in a single patient. We report here 21 patients from 12 unrelated kindreds, homozygous for 12 different mutant alleles that underlie AR IL-17RA deficiency. All patients have isolated CMC and their cells do not respond to IL-17A, -17F, and -17E/IL-25. Chronic mucocutaneous candidiasis (CMC) is defined as recurrent or persistent infection of the skin, nails, and/or mucosae with commensal Candida species. The first genetic etiology of isolated CMC—autosomal recessive (AR) IL-17 receptor A (IL-17RA) deficiency—was reported in 2011, in a single patient. We report here 21 patients with complete AR IL-17RA deficiency, including this first patient. Each patient is homozygous for 1 of 12 different IL-17RA alleles, 8 of which create a premature stop codon upstream from the transmembrane domain and have been predicted and/or shown to prevent expression of the receptor on the surface of circulating leukocytes and dermal fibroblasts. Three other mutant alleles create a premature stop codon downstream from the transmembrane domain, one of which encodes a surface-expressed receptor. Finally, the only known missense allele (p.D387N) also encodes a surface-expressed receptor. All of the alleles tested abolish cellular responses to IL-17A and -17F homodimers and heterodimers in fibroblasts and to IL-17E/IL-25 in leukocytes. The patients are currently aged from 2 to 35 y and originate from 12 unrelated kindreds. All had their first CMC episode by 6 mo of age. Fourteen patients presented various forms of staphylococcal skin disease. Eight were also prone to various bacterial infections of the respiratory tract. Human IL-17RA is, thus, essential for mucocutaneous immunity to Candida and Staphylococcus, but otherwise largely redundant. A diagnosis of AR IL-17RA deficiency should be considered in children or adults with CMC, cutaneous staphylococcal disease, or both, even if IL-17RA is detected on the cell surface.

XLF deficiency results in reduced N-nucleotide addition during V(D)J recombination

Repair of DNA double-strand breaks (DSBs) by the nonhomologous end-joining pathway (NHEJ) is important not only for repair of spontaneous breaks but also for breaks induced in developing lymphocytes during V(D)J (variable [V], diversity [D], and joining [J] genes) recombination of their antigen receptor loci to create a diverse repertoire. Mutations in the NHEJ factor XLF result in extreme sensitivity for ionizing radiation, microcephaly, and growth retardation comparable to mutations in LIG4 and XRCC4, which together form the NHEJ ligation complex. However, the effect on the immune system is variable (mild to severe immunodeficiency) and less prominent than that seen in deficiencies of NHEJ factors ARTEMIS and DNA-dependent protein kinase catalytic subunit, with defects in the hairpin opening step, which is crucial and unique for V(D)J recombination. Therefore, we aimed to study the role of XLF during V(D)J recombination. We obtained clinical data from 9 XLF-deficient patients and performed immune phenotyping and antigen receptor repertoire analysis of immunoglobulin (Ig) and T-cell receptor (TR) rearrangements, using next-generation sequencing in 6 patients. The results were compared with XRCC4 and LIG4 deficiency. Both Ig and TR rearrangements showed a significant decrease in the number of nontemplated (N) nucleotides inserted by terminal deoxynucleotidyl transferase, which resulted in a decrease of 2 to 3 amino acids in the CDR3. Such a reduction in the number of N-nucleotides has a great effect on the junctional diversity, and thereby on the total diversity of the Ig and TR repertoire. This shows that XLF has an important role during V(D)J recombination in creating diversity of the repertoire by stimulating N-nucleotide insertion.

Inherited biallelic CSF3R mutations in severe congenital neutropenia

Severe congenital neutropenia (SCN) is characterized by low numbers of peripheral neutrophil granulocytes and a predisposition to life-threatening bacterial infections. We describe a novel genetic SCN type in 2 unrelated families associated with recessively inherited loss-of-function mutations in CSF3R, encoding the granulocyte colony-stimulating factor (G-CSF) receptor. Family A, with 3 affected children, carried a homozygous missense mutation (NM_000760.3:c.922C>T, NP_000751.1:p.Arg308Cys), which resulted in perturbed N-glycosylation and aberrant localization to the cell surface. Family B, with 1 affected infant, carried compound heterozygous deletions provoking frameshifts and premature stop codons (NM_000760.3:c.948_963del, NP_000751.1:p.Gly316fsTer322 and NM_000760.3:c.1245del, NP_000751.1:p.Gly415fsTer432). Despite peripheral SCN, all patients had morphologic evidence of full myeloid cell maturation in bone marrow. None of the patients responded to treatment with recombinant human G-CSF. Our study highlights the genetic and morphologic SCN variability and provides evidence both for functional importance and redundancy of G-CSF receptor-mediated signaling in human granulopoiesis.

Clinical and molecular aspects of Turkish familial hemophagocytic lymphohistiocytosis patients with perforin mutations

The aim of this study was to elucidate the pathologic sequence changes and associated clinical phenotypes in 9 new patients showing homozygosity for perforin gene among a total of 37 (24%) Turkish FHL families studied by linkage analysis. These 9 unrelated patients (5M/4F) were coming from consanguineous families and their presentation ages of systemic symptoms were ranged from birth to 15 years. Direct sequencing of coding exons of the perforin gene led to the identification of five different homozygous alterations. The nonsense W374X mutation was identified in three patients while four different missense mutations namely G149S, V50M, A91V and novel A523D were detected in the rest six patients.

Increased endothelial microparticles in obese and overweight children.

Abstract Background: Obesity in children increases the risk of atherosclerosis. Endothelial dysfunction is an important factor in the pathogenesis of atherosclerosis, and endothelial microparticles (EMPs) are considered as markers of endothelial dysfunction. In this study, we aimed to evaluate circulating EMPs in obese and overweight children and to disclose the measure of obesity with the strongest relation with circulating microparticles and carotid atherosclerosis. Methods: This prospective study included 55 obese and overweight children and 23 healthy controls. Insulin resistance was studied. Both in vivo and in vitro human umbilical vein endothelial cell evaluations were used for the study. Circulating EMPs (CD144 and CD146) were measured by flow cytometry. The carotid artery intima-media thickness (cIMT) and left ventricular mass index (LVMI) were measured using ultrasound and echocardiography, respectively. Study groups were compared for anthropometric measurement, insulin resistance, circulating EMP, cIMT, and LVMI. The relationship among overweight, obesity, and circulating EMPs were investigated. Results: Blood pressure, CD144+EMP levels, and LVMI were statistically higher in the patients group than in the control group. The multiple logistic regression analysis and the backward elimination method showed that CD144+EMP and systolic blood pressure had a linear relationship with overweight and obesity. Conclusion: Our results suggest that endothelial damage starts in the early stage of childhood obesity and that obese and overweight children have increased circulating CD144+EMPs, showing that endothelial dysfunction and increased CD144+EMPs may be related to obesity.

Recurrent Pulmonary Alveolar Proteinosis Secondary to Agammaglobulinemia

Pulmonary alveolar proteinosis (PAP) is characterized by the accumulation of surfactant derived material in the lung of patients. PAP is rare in children. The patient presented with respiratory failure. In the history she was diagnosed with agammaglobulinemia at 8 months of age and has been treated by IVIG once in a month. She had two pulmonary alveolary proteinosis attacks before. Chest X‐ray showed bilateral diffuse infiltrates. Initial diagnosis were pneumonia, ARDS, and lung edema. Whole‐lung lavage revealed lipoproteinaceous material similar to surfactant. This findings and high level of LDH was as evaluated pulmonary alveolary proteinosis. She discharged from the hospital without any respiratory complication on the ninth day. This is the first case report recurrent PAP associated with agammaglobulinemia. Pediatr Pulmonol. 2008; 43:710–713.

The effect of bovine colostrum on viral upper respiratory tract infections in children with immunoglobulin A deficiency

Introduction:  Immunoglobulin A (IgA)‐deficient patients predominantly suffer from respiratory and gastrointestinal infections since secretory IgA has important functions to protect mucosal surfaces.

Four different NCF2 mutations in six families from Turkey and an overview of NCF2 gene mutations

Background  One of the rarest forms of autosomal recessive chronic granulomatous disease (AR‐CGD) is attributable to mutations in the NCF2 gene, which encodes the polypeptide p67phox, a key cytoplasmic protein in the phagocyte NADPH oxidase system. NCF2 is localized on chromosome 1q25, encompasses 40 kb and contains 16 exons.