Publications by authors named "Krystyna Chrzanowska"

88 Publications

Interfamilial clinical variability in four Polish families with cranioectodermal dysplasia and identical compound heterozygous variants in WDR35.

Am J Med Genet A 2021 04 9;185(4):1195-1203. Epub 2021 Jan 9.

Department of Medical Genetics, Poznan University of Medical Sciences, Poznan, Poland.

Cranioectodermal dysplasia (CED) is a rare autosomal recessive disorder primarily characterized by craniofacial, skeletal, and ectodermal abnormalities. CED is a chondrodysplasia, which is part of a spectrum of clinically and genetically heterogeneous diseases that result from disruptions in cilia. Pathogenic variants in genes encoding components of the ciliary transport machinery are known to cause CED. Intra- and interfamilial clinical variability has been reported in a few CED studies and the findings of this study align with these observations. Here, we report on five CED patients from four Polish families with identical compound heterozygous variants [c.1922T>G p.(Leu641Ter) and c.2522A>T; p.(Asp841Val)] in WDR35. The frequent occurrence of both identified changes in Polish CED families suggests that these variants may be founder mutations. Clinical evaluation of the CED patients revealed interfamilial clinical variability among the patients. This includes differences in skeletal and ectodermal features as well as variability in development, progression, and severity of renal and liver insufficiency. This is the first report showing significant interfamilial clinical variability in a series of CED patients from unrelated families with identical compound heterozygous variants in WDR35. Our findings strongly indicate that other genetic and non-genetic factors may modulate the progression and expression of the patients' phenotypes.
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http://dx.doi.org/10.1002/ajmg.a.62067DOI Listing
April 2021

Variable degree of mosaicism for tetrasomy 18p in phenotypically discordant monozygotic twins-Diagnostic implications.

Mol Genet Genomic Med 2021 01 14;9(1):e1526. Epub 2020 Dec 14.

Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland.

Background: Phenotypically discordant monozygotic twins (PDMZTs) offer a unique opportunity to study post-zygotic genetic variation and provide insights into the linkage between genotype and phenotype. We report a comprehensive analysis of a pair of PDMZTs.

Methods: Dysmorphic features and delayed neuro-motor development were observed in the proband, whereas her twin sister was phenotypically normal. Four tissues (blood, skin, hair follicles, and buccal mucosa) from both twins were studied using four complementary methods, including whole-exome sequencing, karyotyping, array CGH, and SNP array.

Results: In the proband, tetrasomy 18p affecting all studied tissues except for blood was identified. Karyotyping of fibroblasts revealed isochromosome 18p [i(18p)] in all metaphases. The corresponding analysis of the phenotypically normal sister surprisingly revealed low-level mosaicism (5.4%) for i(18p) in fibroblasts.

Conclusion: We emphasize that when mosaicism is suspected, multiple tissues should be studied and we highlight the usefulness of non-invasive sampling of hair follicles and buccal mucosa as a convenient source of non-mesoderm-derived DNA, which complements the analysis of mesoderm using blood. Moreover, low-level mosaic tetrasomy 18p is well tolerated and such low-level mosaicism, readily detected by karyotyping, can be missed by other methods. Finally, mosaicism for low-level tetrasomy 18p might be more common in the general population than it is currently recognized, due to detection limitations.
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http://dx.doi.org/10.1002/mgg3.1526DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7963419PMC
January 2021

X-linked hypophosphatemic rickets in children: clinical phenotype, therapeutic strategies and molecular background.

Endokrynol Pol 2020 Dec 9. Epub 2020 Dec 9.

Poznan University of Medical Sciences, Szpitalna 27/33, 60-572 Poznan, Poland.

Introduction: X-linked HR hypophosphatemic rickets (XLHR) is the most common form HR, which is caused by mutations in the PHEX gene. The aim of this work was to investigate the clinical phenotype, therapeutic strategies and molecular background of HR in children hospitalized in our clinic.

Materials And Methods: Eleven patients aged 5.7-18.25 years were included in this study. Molecular analysis was performed using polymerase chain reaction (PCR) and direct sequencing. The PHEX gene was examined in all of the patients, whereas the FGF23 gene was analyzed in 5 patients. All of them were treated with alfacalcidol and phosphorus, and 3 were treated with recombinant human growth hormone (rhGH).

Results: The mean age at HR diagnosis was 4.05+/-3.35 years. The mean htSDS was -2.99+/-1.19. In the 2 of 3 patients treated with rhGH the height gain was +0.4SD and +0.3SD, respectively. In 10 of 11 patients, PHEX gene mutations were found. In 2 children, novel mutations in the PHEX gene were identified: c.325_326dupCA, N110Ifs*7 in one patient and c.899_900delTG, M300Kfs*4 in the remaining one which coexisted with a known polymorphism c.1769-10C>T, rs3752433. In one patient, a novel deletion of exon 14 and two polymorphisms were detected: c.1646-46T>C, g.180417T>C, rs3213493 in intron 15 (known) and g.189156C>T in intron 17 (novel).

Conclusion: We report 3 novel mutations in the PHEX responsible for HR. Additionally, this study reports the effects of rhGH therapy for growth promotion in HR.
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http://dx.doi.org/10.5603/EP.a2020.0087DOI Listing
December 2020

Occurrence of Portal Hypertension and Its Clinical Course in Patients With Molecularly Confirmed Autosomal Recessive Polycystic Kidney Disease (ARPKD).

Front Pediatr 2020 12;8:591379. Epub 2020 Nov 12.

Department of Gastroenterology, Hepatology, Feeding Disorders and Pediatrics, The Children's Memorial Health Institute, Warsaw, Poland.

Liver involvement in autosomal recessive polycystic kidney disease (ARPKD) leads to the development of portal hypertension and its complications. The aim of this study was to analyze the occurrence of the portal hypertension and its clinical course and the dynamics in patients with molecularly confirmed ARPKD in a large Polish center. Moreover, the available options in diagnostics, prevention and management of portal hypertension in ARPKD will be discussed. The study group consisted of 17 patients aged 2.5-42 years. All patients had ARPKD diagnosis confirmed by molecular tests. Retrospective analysis included laboratory tests, ultrasound and endoscopic examinations, transient elastography and clinical evaluation. Any symptom of portal hypertension was established in 71% of patients. Hypersplenism, splenomegaly, decreased portal flow and esophageal varices were found in 47, 59, 56, and 92% of patients, respectively. Gastrointestinal bleeding occurred in four of 17 patients. Endoscopic variceal ligation (EVL) was performed at least once in nine patients with esophageal varices. Portal hypertension and its complications are present in a significant percentage of ARPKD patients. They should be under the care of multidisciplinary nephrology-gastroenterology/hepatology team. Complications of portal hypertension may occur early in life. Endoscopic methods of preventing gastroesophageal bleeding, such as endoscopic variceal ligation, are effective and surgical techniques, including liver transplantation, are required rarely.
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http://dx.doi.org/10.3389/fped.2020.591379DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7690924PMC
November 2020

Hematopoietic Stem Cell Transplantation Positively Affects the Natural History of Cancer in Nijmegen Breakage Syndrome.

Clin Cancer Res 2021 Jan 20;27(2):575-584. Epub 2020 Oct 20.

Department Pediatrics, Oncology and Hematology, Medical University of Lodz, Lodz, Poland.

Purpose: Nijmegen breakage syndrome (NBS) is a DNA repair disorder with a high predisposition to hematologic malignancies.

Experimental Design: We describe the natural history of NBS, including cancer incidence, risk of death, and the potential effectiveness of hematopoietic stem cell transplantation (HSCT) in preventing both pathologies: malignancy and immunodeficiency.

Results: Among 241 patients with NBS enrolled in the study from 11 countries, 151 (63.0%) patients were diagnosed with cancer. Incidence rates for primary and secondary cancer, tumor characteristics, and risk factors affecting overall survival (OS) were estimated. The cumulative cancer incidence was 40.21% ± 3.5% and 77.78% ± 3.4% at 10 years and 20 years of follow-up, respectively. Most of the tumors = 95 (62.9%) were non-Hodgkin lymphomas. Overall, 20 (13.2%) secondary malignancies occurred at a median age of 18 (interquartile range, 13.7-21.5) years. The probability of 20-year overall survival (OS) for the whole cohort was 44.6% ± 4.5%. Patients who developed cancer had a shorter 20-year OS than those without malignancy (29.6% vs. 86.2%; < 10). A total of 49 patients with NBS underwent HSCT, including 14 patients transplanted before malignancy. Patients with NBS with diagnosed cancer who received HSCT had higher 20-year OS than those who did not (42.7% vs. 30.3%; = 0.038, respectively). In the group of patients who underwent preemptive transplantation, only 1 patient developed cancer, which is 6.7 times lower as compared with nontransplanted patients [incidence rate ratio 0.149 (95% confidence interval, 0.138-0.162); < 0.0001].

Conclusions: There is a beneficial effect of HSCT on the long-term survival of patients with NBS transplanted in their first complete remission of cancer.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-2574DOI Listing
January 2021

Telomere attrition and dysfunction: a potential trigger of the progeroid phenotype in nijmegen breakage syndrome.

Aging (Albany NY) 2020 06 20;12(12):12342-12375. Epub 2020 Jun 20.

Institute of Clinical Chemistry and Laboratory Medicine, University of Rostock, Rostock, Germany.

Background: Nibrin, as part of the NBN/MRE11/RAD50 complex, is mutated in Nijmegen breakage syndrome (NBS), which leads to impaired DNA damage response and lymphoid malignancy.

Results: Telomere length (TL) was markedly reduced in homozygous patients (and comparably so in all chromosomes) by ~40% (qPCR) and was slightly reduced in NBS heterozygotes older than 30 years (~25% in qPCR), in accordance with the respective cancer rates. Humanized cancer-free NBS mice had normal TL. Telomere elongation was inducible by telomerase and/or alternative telomere lengthening but was associated with abnormal expression of telomeric genes involved in aging and/or cell growth. Lymphoblastoid cells from NBS patients with long survival times (>12 years) displayed the shortest telomeres and low caspase 7 activity.

Conclusions: NBS is a secondary telomeropathy. The two-edged sword of telomere attrition enhances the cancer-prone situation in NBS but can also lead to a relatively stable cellular phenotype in tumor survivors. Results suggest a modular model for progeroid syndromes with abnormal expression of telomeric genes as a molecular basis.

Methods: We studied TL and function in 38 homozygous individuals, 27 heterozygotes, one homozygous fetus, six NBS lymphoblastoid cell lines, and humanized NBS mice, all with the same founder mutation: c.657_661del5.
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http://dx.doi.org/10.18632/aging.103453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7343506PMC
June 2020

Breakpoint Mapping of Symptomatic Balanced Translocations Links the , and Genes to Novel Disease Phenotype.

J Clin Med 2020 Apr 25;9(5). Epub 2020 Apr 25.

Department of Medical Genetics, Medical University of Warsaw, 02-106 Warsaw, Poland.

De novo balanced chromosomal aberrations (BCAs), such as reciprocal translocations and inversions, are genomic aberrations that, in approximately 25% of cases, affect the human phenotype. Delineation of the exact structure of BCAs may provide a precise diagnosis and/or point to new disease loci. We report on six patients with de novo balanced chromosomal translocations (BCTs) and one patient with a de novo inversion, in whom we mapped breakpoints to a resolution of 1 bp, using shallow whole-genome mate pair sequencing. In all seven cases, a disruption of at least one gene was found. In two patients, the phenotypic impact of the disrupted genes is well known (). In five patients, the aberration damaged genes: and , whose influence on the human phenotype is poorly understood. In particular, our results suggest novel candidate genes for retinal degeneration with anophthalmia (), developmental delay with speech impairment (), and developmental delay with brain dysembryoplastic neuroepithelial tumor (). In conclusion, identification of the exact structure of symptomatic BCTs using next generation sequencing is a viable method for both diagnosis and finding novel disease candidate genes in humans.
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http://dx.doi.org/10.3390/jcm9051245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7287862PMC
April 2020

The phenotype-driven computational analysis yields clinical diagnosis for patients with atypical manifestations of known intellectual disability syndromes.

Mol Genet Genomic Med 2020 09 26;8(9):e1263. Epub 2020 Apr 26.

Genomics Platform, Berlin Institute of Health, Berlin, Germany.

Background: Due to extensive clinical and genetic heterogeneity of intellectual disability (ID) syndromes, the process of diagnosis is very challenging even for expert clinicians. Despite recent advancements in molecular diagnostics methodologies, a significant fraction of ID patients remains without a clinical diagnosis.

Methods, Results, And Conclusions: Here, in a prospective study on a cohort of 21 families (trios) with a child presenting with ID of unknown etiology, we executed phenotype-driven bioinformatic analysis method, PhenIX, utilizing targeted next-generation sequencing (NGS) data and Human Phenotype Ontology (HPO)-encoded phenotype data. This approach resulted in clinical diagnosis for eight individuals presenting with atypical manifestations of Rubinstein-Taybi syndrome 2 (MIM 613684), Spastic Paraplegia 50 (MIM 612936), Wiedemann-Steiner syndrome (MIM 605130), Cornelia de Lange syndrome 2 (MIM 300590), Cerebral creatine deficiency syndrome 1 (MIM 300352), Glass Syndrome (MIM 612313), Mental retardation, autosomal dominant 31 (MIM 616158), and Bosch-Boonstra-Schaaf optic atrophy syndrome (MIM 615722).
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http://dx.doi.org/10.1002/mgg3.1263DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7507388PMC
September 2020

Rare clinical findings in three sporadic cases of Beckwith-Wiedemann syndrome due to novel mutations in the CDKN1C gene.

Clin Dysmorphol 2020 Jan;29(1):28-34

Department of Medical Genetics, The Children's Memorial Health Institute.

Beckwith-Wiedemann syndrome (BWS) is a rare congenital overgrowth disorder characterised by macroglossia, abdominal wall defects, neonatal hypoglycaemia, lateralised overgrowth and predisposition to embryonal tumours. BWS results mainly from epigenetic changes at chromosome 11p15.5; however, heterozygous pathogenic variants on the maternal CDKN1C allele are observed in 5-8% of sporadic BWS cases. In this study, we report three sporadic BWS patients with novel pathogenic variants in the CDKN1C gene, including one missense (c.181T>C) and two frameshift (c.415_416dup, c.804delC). Detailed clinical evaluation of the patients showed variable manifestation of the disease and underlined the diagnostic challenge for BWS patients at various age of life. The child with the c.415_416dup variant presented with two rare features observed so far in only a few BWS patients with CDKN1C pathogenic variants: supernumerary flexion creases and agenesis of corpus callosum. Confirmation of these findings in another BWS patient adds to the broad clinical spectrum of the disease and suggests that presence of these features may be associated with CDKN1C pathogenic variants.
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http://dx.doi.org/10.1097/MCD.0000000000000307DOI Listing
January 2020

Genetic Spectrum of -Associated Retinal Degeneration in Poland.

Genes (Basel) 2019 11 21;10(12). Epub 2019 Nov 21.

Children's Memorial Health Institute, 04-730 Warsaw, Poland.

Mutations in retina-specific ATP-binding cassette transporter 4 () are responsible for over 95% of cases of Stargardt disease (STGD), as well as a minor proportion of retinitis pigmentosa (RP) and cone-rod dystrophy cases (CRD). Since the knowledge of the genetic causes of inherited retinal diseases (IRDs) in Poland is still scarce, the purpose of this study was to identify pathogenic variants in a subgroup of Polish IRD patients. We recruited 67 families with IRDs as a part of a larger study. The patients were screened with next generation sequencing using a molecular inversion probes (MIPs)-based technique targeting 108 genes involved in the pathogenesis of IRDs. All identified mutations were validated and their familial segregation was tested using Sanger sequencing. In the case of the most frequent complex allele, consisting of two variants in exon 12 and 21, familial segregation was tested using restriction fragment length polymorphism (RFLP). The most prevalent variant, a complex change c.[1622T>C;3113C>T], p.[Leu541Pro;Ala1038Val], was found in this cohort in 54% of all solved -associated disorder cases, which is the highest frequency reported thus far. Additionally, we identified nine families displaying a pseudo-dominant mode of inheritance, indicating a high frequency of pathogenic variants within this population.
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http://dx.doi.org/10.3390/genes10120959DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6947411PMC
November 2019

A case of premature ovarian insufficiency in Nijmegen breakage syndrome patient and review of literature. From gene mutation to clinical management.

Gynecol Endocrinol 2019 Nov 12;35(11):999-1002. Epub 2019 Jun 12.

Department of Gynecological Endocrinology, Poznan University of Medical Sciences , Poznan , Poland.

Nijmegen breakage syndrome (NBS) is an autosomal recessive disorder leading to chromosomal instability and an array of symptoms, including characteristic facial features (bird-like face), predisposition to malignancies, as well as hypergonadotropic hypogonadism. This case report discusses the diagnostic process and management of a 23-year-old Polish female patient who was admitted to hospital with symptoms of secondary amenorrhea and clinical features corresponding to NBS. Clinical examination, per-rectal ultrasound, laboratory diagnostics (including serum concentrations of FSH, LH, estradiol, testosterone, and TSH), as well as SSCP analysis and classic karyotyping were performed. During hormonal evaluation elevated serum concentration of FSH and LH and decreased serum concentration of estradiol were measured. The genetic testing revealed translocation 7;14 (t(7;14)) and inversion 7 in 22% of examined cells which confirmed the initial hypothesis of NBS. The diagnosis was finally verified by identifying a Slavic founder mutation, c.657_661del5, on both allels of the gene. Furthermore, hormonal serum evaluation conducted after four weeks allowed the patient to be diagnosed with premature ovarian insufficiency (POI) suspected earlier on the grounds of preliminary examinations (ultrasound imaging and laboratory tests). Chromosomal instability resulting from a mutation present in Nijmegen breakage syndrome patients might be a causative factor of premature ovarian insufficiency. Therefore, females diagnosed with NBS should undergo additional diagnostic procedures in order to determine further management and treatment.
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http://dx.doi.org/10.1080/09513590.2019.1626366DOI Listing
November 2019

Correction: The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin-Siris syndrome.

Authors:
Pleuntje J van der Sluijs Sandra Jansen Samantha A Vergano Miho Adachi-Fukuda Yasemin Alanay Adila AlKindy Anwar Baban Allan Bayat Stefanie Beck-Wödl Katherine Berry Emilia K Bijlsma Levinus A Bok Alwin F J Brouwer Ineke van der Burgt Philippe M Campeau Natalie Canham Krystyna Chrzanowska Yoyo W Y Chu Brain H Y Chung Karin Dahan Marjan De Rademaeker Anne Destree Tracy Dudding-Byth Rachel Earl Nursel Elcioglu Ellen R Elias Christina Fagerberg Alice Gardham Blanca Gener Erica H Gerkes Ute Grasshoff Arie van Haeringen Karin R Heitink Johanna C Herkert Nicolette S den Hollander Denise Horn David Hunt Sarina G Kant Mitsuhiro Kato Hülya Kayserili Rogier Kersseboom Esra Kilic Malgorzata Krajewska-Walasek Kylin Lammers Lone W Laulund Damien Lederer Melissa Lees Vanesa López-González Saskia Maas Grazia M S Mancini Carlo Marcelis Francisco Martinez Isabelle Maystadt Marianne McGuire Shane McKee Sarju Mehta Kay Metcalfe Jeff Milunsky Seiji Mizuno John B Moeschler Christian Netzer Charlotte W Ockeloen Barbara Oehl-Jaschkowitz Nobuhiko Okamoto Sharon N M Olminkhof Carmen Orellana Laurent Pasquier Caroline Pottinger Vera Riehmer Stephen P Robertson Maian Roifman Caroline Rooryck Fabienne G Ropers Monica Rosello Claudia A L Ruivenkamp Mahmut S Sagiroglu Suzanne C E H Sallevelt Amparo Sanchis Calvo Pelin O Simsek-Kiper Gabriela Soares Lucia Solaeche Fatma Mujgan Sonmez Miranda Splitt Duco Steenbeek Alexander P A Stegmann Constance T R M Stumpel Saori Tanabe Eyyup Uctepe G Eda Utine Hermine E Veenstra-Knol Sunita Venkateswaran Catheline Vilain Catherine Vincent-Delorme Anneke T Vulto-van Silfhout Patricia Wheeler Golder N Wilson Louise C Wilson Bernd Wollnik Tomoki Kosho Dagmar Wieczorek Evan Eichler Rolph Pfundt Bert B A de Vries Jill Clayton-Smith Gijs W E Santen

Genet Med 2019 Sep;21(9):2160-2161

Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.

The original version of this Article contained an error in the spelling of the author Pleuntje J. van der Sluijs, which was incorrectly given as Eline (P. J.) van der Sluijs. This has now been corrected in both the PDF and HTML versions of the Article.
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http://dx.doi.org/10.1038/s41436-018-0368-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6752317PMC
September 2019

Transient Elastography for Detection of Liver Fibrosis in Children With Autosomal Recessive Polycystic Kidney Disease.

Front Pediatr 2018 11;6:422. Epub 2019 Jan 11.

Department of Gastroenterology, Hepatology, Feeding Disorders and Pediatrics, Children's Memorial Health Institute, Warsaw, Poland.

Congenital hepatic fibrosis (CHF) is invariably present in all patients with autosomal recessive polycystic kidney disease (ARPKD) but is usually clinically asymptomatic. The portal hypertension in the course of CHF develops and progresses over time, so an early detection of liver fibrosis remains crucial. The aim of the study was to evaluate a predictive value of transient elastography for evaluating liver disease progress in pediatric ARPKD patients. The study group encompassed 21 pediatric patients with ARPKD and 20 healthy children (control group) from The Children's Memorial Health Institute in Warsaw, Poland. Liver fibrosis was determined by assessing the liver stiffness (LS) with transient elastography (FibroScan®, FS) using size-appropriate probes. In ARPKD group the laboratory findings, results of an abdominal ultrasound examination, and an endoscopic gastroduodenoscopy were also analyzed. Compared with healthy controls, patients with ARPKD had significantly increased median LS values (22 vs. 4.25 kPa, < 0.0001). Based on FS results, ARPKD group was divided into two subgroups: patients ( = 5) with LS results suggestive of no fibrosis or minimal fibrosis (LS < 6.9 kPa, METAVIR fibrosis stage 0-1) and patients ( = 16) with LS results suggestive of at least significant liver fibrosis (LS ≥ 6.9 kPa, METAVIR fibrosis stage 2-4). In the first subgroup (no fibrosis or minimal fibrosis), all patients had no signs of portal hypertension. In the subgroup with at least significant liver fibrosis, splenomegaly was observed in 87.5% of patients and thrombocytopenia in 69% of patients. An endoscopic gastroduodenoscopy was performed in 15 out of 21 ARPKD patients, nine patients (60%) had esophageal varices. All of these patients had LS results suggestive of at least significant liver fibrosis. TE by FibroScan can be used as an additional method for evaluating liver disease progress in pediatric ARPKD patients.
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http://dx.doi.org/10.3389/fped.2018.00422DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336693PMC
January 2019

DNA damage and transcriptional regulation in iPSC-derived neurons from Ataxia Telangiectasia patients.

Sci Rep 2019 01 24;9(1):651. Epub 2019 Jan 24.

Department of Research, Fondazione IRCCS Istituto Nazionale Tumori, Milano, Via Amadeo 42, 20133, Milano, Italy.

Ataxia Telangiectasia (A-T) is neurodegenerative syndrome caused by inherited mutations inactivating the ATM kinase, a master regulator of the DNA damage response (DDR). What makes neurons vulnerable to ATM loss remains unclear. In this study we assessed on human iPSC-derived neurons whether the abnormal accumulation of DNA-Topoisomerase 1 adducts (Top1ccs) found in A-T impairs transcription elongation, thus favoring neurodegeneration. Furthermore, whether neuronal activity-induced immediate early genes (IEGs), a process involving the formation of DNA breaks, is affected by ATM deficiency. We found that Top1cc trapping by CPT induces an ATM-dependent DDR as well as an ATM-independent induction of IEGs and repression especially of long genes. As revealed by nascent RNA sequencing, transcriptional elongation and recovery were found to proceed with the same rate, irrespective of gene length and ATM status. Neuronal activity induced by glutamate receptors stimulation, or membrane depolarization with KCl, triggered a DDR and expression of IEGs, the latter independent of ATM. In unperturbed A-T neurons a set of genes (FN1, DCN, RASGRF1, FZD1, EOMES, SHH, NR2E1) implicated in the development, maintenance and physiology of central nervous system was specifically downregulated, underscoring their potential involvement in the neurodegenerative process in A-T patients.
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http://dx.doi.org/10.1038/s41598-018-36912-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6346060PMC
January 2019

Fibroblast-derived integration-free iPSC line ISRM-NBS1 from an 18-year-old Nijmegen Breakage Syndrome patient carrying the homozygous NBN c.657_661del5 mutation.

Stem Cell Res 2019 01 27;34:101372. Epub 2018 Dec 27.

Institute for Stem Cell Research and Regenerative Medicine, Medical Faculty, Heinrich-Heine-University Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany. Electronic address:

Human fibroblasts cells from a female diagnosed with Nijmegen Breakage Syndrome (NBS) carrying the homozygous NBN c.657_661del5 mutation were used to generate integration-free induced pluripotent stem cells (iPSCs) by over-expressing episomal-based plasmids harbouring OCT4, SOX2, NANOG, KLF4, c-MYC and LIN28. The derived iPSC line - ISRM-NBS1 was defined as pluripotent based on (i) expression of pluripotency-associated markers (ii) embryoid body-based differentiation into cell types representative of the three germ layers and (iii) the similarity between the transcriptome of the iPSC line and the human embryonic stem cell line H1 with a Pearson correlation of 0.955.
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http://dx.doi.org/10.1016/j.scr.2018.101372DOI Listing
January 2019

The frequency of mitochondrial polymerase gamma related disorders in a large Polish population cohort.

Mitochondrion 2019 07 10;47:179-187. Epub 2018 Nov 10.

Department of Medical Genetics, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland; Department of Pediatrics, Nutrition and Metabolic Disorders, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland.

Diseases related to DNA polymerase gamma dysfunction comprise of heterogeneous clinical presentations with variable severity and age of onset. Molecular screening for the common POLG variants: p.Ala467Thr, p.Trp748Ser, p.Gly848Ser, and p.Tre251Ile has been conducted in a large population cohort (n = 3123) and in a clinically heterogeneous group of 1289 patients. Recessive pathogenic variants, including six novel ones were revealed in 22/26 patients. Infantile Alpers-Huttenlocher syndrome and adulthood ataxia spectrum were the most common found in our group. Distinct molecular profile identified in the Polish patients with significant predominance of p.Trp748Ser variant (50% of mutant alleles) reflected strikingly low population frequency of the three remaining variants and slightly higher p.Trp748Ser allele frequency in the general Polish population as compared to the non-Finish European population.
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http://dx.doi.org/10.1016/j.mito.2018.11.004DOI Listing
July 2019

Small supernumerary marker chromosomes: A legacy of trisomy rescue?

Hum Mutat 2019 02 22;40(2):193-200. Epub 2018 Nov 22.

Department of Molecular Medicine, University of Pavia, Pavia, Italy.

We studied by a whole genomic approach and trios genotyping, 12 de novo, nonrecurrent small supernumerary marker chromosomes (sSMC), detected as mosaics during pre- or postnatal diagnosis and associated with increased maternal age. Four sSMCs contained pericentromeric portions only, whereas eight had additional non-contiguous portions of the same chromosome, assembled together in a disordered fashion by repair-based mechanisms in a chromothriptic event. Maternal hetero/isodisomy was detected with a paternal origin of the sSMC in some cases, whereas in others two maternal alleles in the sSMC region and biparental haplotypes of the homologs were detected. In other cases, the homologs were biparental while the sSMC had the same haplotype of the maternally inherited chromosome. These findings strongly suggest that most sSMCs are the result of a multiple-step mechanism, initiated by maternal meiotic nondisjunction followed by postzygotic anaphase lagging of the supernumerary chromosome and its subsequent chromothripsis.
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http://dx.doi.org/10.1002/humu.23683DOI Listing
February 2019

Mapping of breakpoints in balanced chromosomal translocations by shallow whole-genome sequencing points to , and as novel candidates for genes causing human Mendelian disorders.

J Med Genet 2019 02 23;56(2):104-112. Epub 2018 Oct 23.

Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland.

Background: Mapping the breakpoints in de novo balanced chromosomal translocations (BCT) in symptomatic individuals provides a unique opportunity to identify in an unbiased way the likely causative genetic defect and thus find novel human disease candidate genes. Our aim was to fine-map breakpoints of de novo BCTs in a case series of nine patients.

Methods: Shallow whole-genome mate pair sequencing (SGMPS) together with long-range PCR and Sanger sequencing. In one case (BCT disrupting and ) cDNA analysis was used to verify expression of a fusion transcript in cultured fibroblasts.

Results: In all nine probands 11 disrupted genes were found, that is, and . Five subjects had translocations that disrupted genes with so far unknown () or poorly delineated impact on the phenotype ( two previous reports of BCT disrupting the gene). The four genes with no previous disease associations (), when compared with all human genes by a bootstrap test, had significantly higher pLI (p<0.017) and DOMINO (p<0.02) scores indicating enrichment in genes likely to be intolerant to single copy damage. Inspection of individual pLI and DOMINO scores, and local topologically associating domain structure suggested that and were particularly good candidates for novel disease loci. The pathomechanism for may involve deregulation of expression due to fusion with promoter.

Conclusion: SGMPS in symptomatic carriers of BCTs is a powerful approach to delineate novel human gene-disease associations.
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http://dx.doi.org/10.1136/jmedgenet-2018-105527DOI Listing
February 2019

The ARID1B spectrum in 143 patients: from nonsyndromic intellectual disability to Coffin-Siris syndrome.

Authors:
Pleuntje J van der Sluijs Sandra Jansen Samantha A Vergano Miho Adachi-Fukuda Yasemin Alanay Adila AlKindy Anwar Baban Allan Bayat Stefanie Beck-Wödl Katherine Berry Emilia K Bijlsma Levinus A Bok Alwin F J Brouwer Ineke van der Burgt Philippe M Campeau Natalie Canham Krystyna Chrzanowska Yoyo W Y Chu Brain H Y Chung Karin Dahan Marjan De Rademaeker Anne Destree Tracy Dudding-Byth Rachel Earl Nursel Elcioglu Ellen R Elias Christina Fagerberg Alice Gardham Blanca Gener Erica H Gerkes Ute Grasshoff Arie van Haeringen Karin R Heitink Johanna C Herkert Nicolette S den Hollander Denise Horn David Hunt Sarina G Kant Mitsuhiro Kato Hülya Kayserili Rogier Kersseboom Esra Kilic Malgorzata Krajewska-Walasek Kylin Lammers Lone W Laulund Damien Lederer Melissa Lees Vanesa López-González Saskia Maas Grazia M S Mancini Carlo Marcelis Francisco Martinez Isabelle Maystadt Marianne McGuire Shane McKee Sarju Mehta Kay Metcalfe Jeff Milunsky Seiji Mizuno John B Moeschler Christian Netzer Charlotte W Ockeloen Barbara Oehl-Jaschkowitz Nobuhiko Okamoto Sharon N M Olminkhof Carmen Orellana Laurent Pasquier Caroline Pottinger Vera Riehmer Stephen P Robertson Maian Roifman Caroline Rooryck Fabienne G Ropers Monica Rosello Claudia A L Ruivenkamp Mahmut S Sagiroglu Suzanne C E H Sallevelt Amparo Sanchis Calvo Pelin O Simsek-Kiper Gabriela Soares Lucia Solaeche Fatma Mujgan Sonmez Miranda Splitt Duco Steenbeek Alexander P A Stegmann Constance T R M Stumpel Saori Tanabe Eyyup Uctepe G Eda Utine Hermine E Veenstra-Knol Sunita Venkateswaran Catheline Vilain Catherine Vincent-Delorme Anneke T Vulto-van Silfhout Patricia Wheeler Golder N Wilson Louise C Wilson Bernd Wollnik Tomoki Kosho Dagmar Wieczorek Evan Eichler Rolph Pfundt Bert B A de Vries Jill Clayton-Smith Gijs W E Santen

Genet Med 2019 06 8;21(6):1295-1307. Epub 2018 Nov 8.

Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.

Purpose: Pathogenic variants in ARID1B are one of the most frequent causes of intellectual disability (ID) as determined by large-scale exome sequencing studies. Most studies published thus far describe clinically diagnosed Coffin-Siris patients (ARID1B-CSS) and it is unclear whether these data are representative for patients identified through sequencing of unbiased ID cohorts (ARID1B-ID). We therefore sought to determine genotypic and phenotypic differences between ARID1B-ID and ARID1B-CSS. In parallel, we investigated the effect of different methods of phenotype reporting.

Methods: Clinicians entered clinical data in an extensive web-based survey.

Results: 79 ARID1B-CSS and 64 ARID1B-ID patients were included. CSS-associated dysmorphic features, such as thick eyebrows, long eyelashes, thick alae nasi, long and/or broad philtrum, small nails and small or absent fifth distal phalanx and hypertrichosis, were observed significantly more often (p < 0.001) in ARID1B-CSS patients. No other significant differences were identified.

Conclusion: There are only minor differences between ARID1B-ID and ARID1B-CSS patients. ARID1B-related disorders seem to consist of a spectrum, and patients should be managed similarly. We demonstrated that data collection methods without an explicit option to report the absence of a feature (such as most Human Phenotype Ontology-based methods) tended to underestimate gene-related features.
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http://dx.doi.org/10.1038/s41436-018-0330-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6752273PMC
June 2019

Correction to: Circulating T Cells of Patients with Nijmegen Breakage Syndrome Show Signs of Senescence.

J Clin Immunol 2018 May;38(4):538

Department of Immunology, Laboratory for Medical Immunology, Erasmus MC, University Medical Center Rotterdam, Wytemaweg 80, 3015, CN, Rotterdam, The Netherlands.

The original version of the article, "Circulating T Cells of Patients with Nijmegen Breakage Syndrome Show Signs of Senescence" incorrectly listed the affiliation of the fourth author, Iwona Solarska. The correct affiliation is "Molecular Biology Laboratory, Institute of Hematology and Transfusion Medicine.
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http://dx.doi.org/10.1007/s10875-018-0503-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6828370PMC
May 2018

Evidence for a pre-malignant cell line in a skin biopsy from a patient with Nijmegen breakage syndrome.

Mol Cytogenet 2018 7;11:17. Epub 2018 Feb 7.

4Department of Medical Genetics, The Children's Memorial Health Institute, Warsaw, Poland.

Background: Nijmegen breakage syndrome is an autosomal recessive disorder characterized by microcephaly, immunodeficiency, hypersensitivity to X-irradiation, and a high predisposition to cancer. Nibrin, the product of the gene, is part of the MRE11/RAD50 (MRN) complex that is involved in the repair of DNA double strand breaks (DSBs), and plays a critical role in the processing of DSBs in immune gene rearrangements, telomere maintenance, and meiotic recombination. NBS skin fibroblasts grow slowly in culture and enter early into senescence.

Case Presentation: Here we present an incidental finding. Skin fibroblasts, derived from a 9 year old NBS patient, showed a mosaic of normal diploid cells (46,XY) and those with a complex, unbalanced translocation. The aberrant karyotype was analysed by G-banding, comparative genomic hybridization, and whole chromosome painting. The exact breakpoints of the derivative chromosome were mapped by whole genome sequencing: 45,XY,der(6)(6pter → 6q11.1::13q11 → 13q21.33::20q11.22 → 20qter),-13. The deleted region of chromosomes 6 harbors almost 1.400 and that of chromosome 13 more than 500 genes, the duplicated region of chromosome 20 contains about 700 genes. Such unbalanced translocations are regularly incompatible with cellular survival, except in malignant cells. The aberrant cells, however, showed a high proliferation potential and could even be clonally expanded. Telomere length was significantly reduced, was not expressed. The cells underwent about 50 population doublings until they entered into senescence. The chromosomal preparation performed shortly before senescence showed telomere fusions, premature centromere divisions, endoreduplications and tetraploid cells, isochromatid breaks and a variety of marker chromosomes. Inspection of the site of skin biopsy 18 years later, presented no evidence for abnormal growth.

Conclusions: The aberrant cells had a significant selective advantage in vitro. It is therefore tempting to speculate that this highly unbalanced translocation could be a primary driver of cancer cell growth.
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http://dx.doi.org/10.1186/s13039-018-0364-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5803995PMC
February 2018

Constitutional mosaicism of a de novo TP53 mutation in a patient with bilateral choroid plexus carcinoma.

Cancer Genet 2017 Oct 20;216-217:79-85. Epub 2017 Jul 20.

Department of Oncology, The Children's Memorial Health Institute, 04-730 Warsaw, Poland.

Choroid plexus tumors (CPT) constitute 2%-5% of all pediatric brain tumors and include high grade choroid plexus carcinoma (CPC). About 40% of CPC patients harbor germline TP53 mutations, associated with diminished survival rates. However, the number of TP53 carriers might be underestimated due to suboptimal ability of Sanger sequencing to identify mosaicism. We describe an 18-month-old boy with ultra-rare, bilateral disseminated CPC and negative family history of cancer. Next generation sequencing (NGS) revealed constitutional mosaicism of de novo TP53 mutation, which was barely detectable by Sanger sequencing. This is the first description of a de novo TP53 mutation mosaicism in a patient with CPC. Up to now four cases of de novo TP53 mutations in CPC patients have been described but none of them were mosaic. Since TP53 mutation mosaicism may have an impact on management of patients and predisposition to other cancers, a reliable method of identification is important. Our results highlight the utility of high-throughput technologies in detection of potentially important genetic markers.
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http://dx.doi.org/10.1016/j.cancergen.2017.07.001DOI Listing
October 2017

Anemia in Patients With Resistance to Thyroid Hormone α: A Role for Thyroid Hormone Receptor α in Human Erythropoiesis.

J Clin Endocrinol Metab 2017 09;102(9):3517-3525

Department of Internal Medicine, Erasmus University Medical Center, 3000 Rotterdam, The Netherlands.

Context: Patients with resistance to thyroid hormone (TH) α (RTHα) are characterized by growth retardation, macrocephaly, constipation, and abnormal thyroid function tests. In addition, almost all RTHα patients have mild anemia, the pathogenesis of which is unknown. Animal studies suggest an important role for TH and TH receptor (TR)α in erythropoiesis.

Objective: To investigate whether a defect in TRα affects the maturation of red blood cells in RTHα patients.

Design, Setting, And Patients: Cultures of primary human erythroid progenitor cells (HEPs), from peripheral blood of RTHα patients (n = 11) harboring different inactivating mutations in TRα (P398R, F397fs406X, C392X, R384H, A382fs388X, A263V, A263S), were compared with healthy controls (n = 11). During differentiation, erythroid cells become smaller, accumulate hemoglobin, and express different cell surface markers. We assessed cell number and cell size, and used cell staining and fluorescence-activated cell sorter analysis to monitor maturation at different time points.

Results: After ∼14 days of ex vivo expansion, both control and patient-derived progenitors differentiated spontaneously. However, RTHα-derived cells differentiated more slowly. During spontaneous differentiation, RTHα-derived HEPs were larger, more positive for c-Kit (a proliferation marker), and less positive for glycophorin A (a differentiation marker). The degree of abnormal spontaneous maturation of RTHα-derived progenitors did not correlate with severity of underlying TRα defect. Both control and RTHα-derived progenitors responded similarly when differentiation was induced. T3 exposure accelerated differentiation of both control- and RTHα patient-derived HEPs.

Conclusions: Inactivating mutations in human TRα affect the balance between proliferation and differentiation of progenitor cells during erythropoiesis, which may contribute to the mild anemia seen in most RTHα patients.
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http://dx.doi.org/10.1210/jc.2017-00840DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5587074PMC
September 2017

The germline variants in DNA repair genes in pediatric medulloblastoma: a challenge for current therapeutic strategies.

BMC Cancer 2017 04 4;17(1):239. Epub 2017 Apr 4.

Department of Pathology, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730, Warsaw, Poland.

Background: The defects in DNA repair genes are potentially linked to development and response to therapy in medulloblastoma. Therefore the purpose of this study was to establish the spectrum and frequency of germline variants in selected DNA repair genes and their impact on response to chemotherapy in medulloblastoma patients.

Methods: The following genes were investigated in 102 paediatric patients: MSH2 and RAD50 using targeted gene panel sequencing and NBN variants (p.I171V and p.K219fs*19) by Sanger sequencing. In three patients with presence of rare life-threatening adverse events (AE) and no detected variants in the analyzed genes, whole exome sequencing was performed. Based on combination of molecular and immunohistochemical evaluations tumors were divided into molecular subgroups. Presence of variants was tested for potential association with the occurrence of rare life-threatening AE and other clinical features.

Results: We have identified altogether six new potentially pathogenic variants in MSH2 (p.A733T and p.V606I), RAD50 (p.R1093*), FANCM (p.L694*), ERCC2 (p.R695C) and EXO1 (p.V738L), in addition to two known NBN variants. Five out of twelve patients with defects in either of MSH2, RAD50 and NBN genes suffered from rare life-threatening AE, more frequently than in control group (p = 0.0005). When all detected variants were taken into account, the majority of patients (8 out of 15) suffered from life-threatening toxicity during chemotherapy.

Conclusion: Our results, based on the largest systematic study performed in a clinical setting, provide preliminary evidence for a link between defects in DNA repair genes and treatment related toxicity in children with medulloblastoma. The data suggest that patients with DNA repair gene variants could need special vigilance during and after courses of chemotherapy.
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http://dx.doi.org/10.1186/s12885-017-3211-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5379555PMC
April 2017

Intrafamilial phenotypic variability in a Polish family with Sensenbrenner syndrome and biallelic WDR35 mutations.

Am J Med Genet A 2017 May 23;173(5):1364-1368. Epub 2017 Mar 23.

Department of Medical Genetics, The Children's Memorial Health Institute, Warsaw, Poland.

Sensenbrenner syndrome (cranioectodermal dysplasia, CED) is a very rare autosomal recessive ciliopathy. Cranioectodermal dysplasia is characterized by craniofacial, skeletal, and ectodermal abnormalities. About 50 patients have been described to date. Sensenbrenner syndrome belongs to a group of ciliary chondrodysplasias and is a genetically heterogeneous disorder. Mutations in five genes: IFT122, WDR35, IFT43, WDR19, and IFT52 have been associated with CED. All known genes encode proteins that are part of the intraflagellar transport complex, which plays an important role in the assembly and maintenance of cilia. Here, we report a family with two children affected by Sensenbrenner syndrome, a 9-year-old girl and her older sister who died in infancy due to respiratory, liver, and renal insufficiency. Dysmorphic features included short stature with rhizomelic shortening of limbs, short fingers, preaxial polydactyly of left hand, narrow chest, craniosynostosis, dolichocephaly, high anterior hairline, epicanthal folds and telecanthus, depressed nasal bridge, low-set ears, and additional ectodermal abnormalities. The patient presented with chronic tubulointerstitial renal disease. She had abnormal echogenicity on renal ultrasound, reduced glomerular filtration, albuminuria and tubular proteinuria, hypocalciuria and hypocitraturia, accompanied by pre-hypertensive state. This pattern of renal abnormality was regarded as nephronophthisis. Psychomotor development was apparently normal. Molecular analysis in one of the affected individuals identified compound heterozygosity for a nonsense (c.1922T>G, p.(Leu641*)) and missense (c.2522A>T, p.(Asp841Val)) variants in WDR35. We present a detailed clinical descriptions of two female siblings showing an intrafamilial phenotypic variability of the disease, and illustrating the potential lethality of CED.
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http://dx.doi.org/10.1002/ajmg.a.38163DOI Listing
May 2017

Novel pathogenic variant in the HRAS gene with lethal outcome and a broad phenotypic spectrum among Polish patients with Costello syndrome.

Clin Dysmorphol 2017 Apr;26(2):83-90

aDepartment of Medical Genetics, The Children's Memorial Health Institute bDepartment of Paediatrics, Medical University of Warsaw, Warsaw cDepartment of Medical Genetics, Medical College, Jagiellonian University, Cracov, Poland.

Costello syndrome (CS) is a rare congenital disorder from the group of RASopathies, characterized by a distinctive facial appearance, failure to thrive, cardiac and skin anomalies, intellectual disability, and a predisposition to neoplasia. CS is associated with germline mutations in the proto-oncogene HRAS, a small GTPase from the Ras family. In this study, a molecular and clinical analysis was carried out in eight Polish patients with the Costello phenotype. A molecular test showed two known heterozygous mutations in the first coding exon of the gene in seven patients: p.G12S (n=4) and p.G12A (n=3), and a novel pathogenic variant p.G60V in one child with an unusually severe, lethal course of the syndrome. In addition, a fatal course of CS was present in one patient with the p.G12A mutation and in another with p.G12S, there was a co-occurrence of Turner syndrome because of the distal Xp deletion. A severe clinical manifestation with a lethal outcome in an individual with p.G60V in HRAS and contrary observations of an attenuated phenotype in CS patients with other mutations at glycine-60 residue may suggest that the nature of the substituted amino acid plays a significant role in the clinical variability observed in some CS cases.
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http://dx.doi.org/10.1097/MCD.0000000000000165DOI Listing
April 2017

Circulating T Cells of Patients with Nijmegen Breakage Syndrome Show Signs of Senescence.

J Clin Immunol 2017 Feb 21;37(2):133-142. Epub 2016 Dec 21.

Department of Immunology, Laboratory for Medical Immunology, Erasmus MC, University Medical Center Rotterdam, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.

Purpose: The Nijmegen breakage syndrome (NBS) is an inherited genetic disorder characterized by a typical facial appearance, microcephaly, growth retardation, immunodeficiency, and a strong predisposition to malignancies, especially of lymphoid origin. NBS patients have a mutation in the NBN gene which involves the repair of DNA double-strand breaks (DSBs). Here we studied the peripheral T cell compartment of NBS patients with a focus on immunological senescence.

Methods: The absolute numbers and frequencies of the different T cell subsets were determined in NBS patients from young age till adulthood and compared to age-matched healthy individuals (HI). In addition, we determined the expression of senescent T cell markers and the signal joint T cell receptor excision circles (sjTRECs) content.

Results: Our results demonstrate that NBS patients have reduced T cell numbers. NBS patients showed lower numbers of αβ T cells, but normal γδ T cell numbers compared to HI. Concerning the αβ T cells, both CD4 as well as CD8 T cells were excessively reduced in numbers compared to aged-matched HI. In addition, NBS patients showed higher frequencies of the more differentiated T cells expressing the senescent cell marker CD57 and did not express co-stimulatory molecule CD28. These effects were already present in the youngest age group. Furthermore, NBS patients showed lower sjTREC content in their T cells possibly indicative of a lower thymic output.

Conclusions: We conclude that circulating T cells from NBS patients show signs of a senescent phenotype which is already present from young age on and which might explain their T cell immune deficiency.
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http://dx.doi.org/10.1007/s10875-016-0363-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5325864PMC
February 2017

The Slavic NBN Founder Mutation: A Role for Reproductive Fitness?

PLoS One 2016 9;11(12):e0167984. Epub 2016 Dec 9.

Cologne Center for Genomics, University of Cologne, Köln, Germany.

The vast majority of patients with Nijmegen Breakage Syndrome (NBS) are of Slavic origin and carry a deleterious deletion (c.657del5; rs587776650) in the NBN gene on chromosome 8q21. This mutation is essentially confined to Slavic populations and may thus be considered a Slavic founder mutation. Notably, not a single parenthood of a homozygous c.657del5 carrier has been reported to date, while heterozygous carriers do reproduce but have an increased cancer risk. These observations seem to conflict with the considerable carrier frequency of c.657del5 of 0.5% to 1% as observed in different Slavic populations because deleterious mutations would be eliminated quite rapidly by purifying selection. Therefore, we propose that heterozygous c.657del5 carriers have increased reproductive success, i.e., that the mutation confers heterozygote advantage. In fact, in our cohort study of the reproductive history of 24 NBS pedigrees from the Czech Republic, we observed that female carriers gave birth to more children on average than female non-carriers, while no such reproductive differences were observed for males. We also estimate that c.657del5 likely occurred less than 300 generations ago, thus supporting the view that the original mutation predated the historic split and subsequent spread of the 'Slavic people'. We surmise that the higher fertility of female c.657del5 carriers reflects a lower miscarriage rate in these women, thereby reflecting the role of the NBN gene product, nibrin, in the repair of DNA double strand breaks and their processing in immune gene rearrangements, telomere maintenance, and meiotic recombination, akin to the previously described role of the DNA repair genes BRCA1 and BRCA2.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0167984PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5148078PMC
July 2017

Diagnosis and management of Silver-Russell syndrome: first international consensus statement.

Nat Rev Endocrinol 2017 02 2;13(2):105-124. Epub 2016 Sep 2.

AP-HP, Hôpitaux Universitaires Paris Est (AP-HP) Hôpital des Enfants Armand Trousseau, Service d'Explorations Fonctionnelles Endocriniennes, 26 avenue du Dr Arnold Netter, 75012 Paris, France.

This Consensus Statement summarizes recommendations for clinical diagnosis, investigation and management of patients with Silver-Russell syndrome (SRS), an imprinting disorder that causes prenatal and postnatal growth retardation. Considerable overlap exists between the care of individuals born small for gestational age and those with SRS. However, many specific management issues exist and evidence from controlled trials remains limited. SRS is primarily a clinical diagnosis; however, molecular testing enables confirmation of the clinical diagnosis and defines the subtype. A 'normal' result from a molecular test does not exclude the diagnosis of SRS. The management of children with SRS requires an experienced, multidisciplinary approach. Specific issues include growth failure, severe feeding difficulties, gastrointestinal problems, hypoglycaemia, body asymmetry, scoliosis, motor and speech delay and psychosocial challenges. An early emphasis on adequate nutritional status is important, with awareness that rapid postnatal weight gain might lead to subsequent increased risk of metabolic disorders. The benefits of treating patients with SRS with growth hormone include improved body composition, motor development and appetite, reduced risk of hypoglycaemia and increased height. Clinicians should be aware of possible premature adrenarche, fairly early and rapid central puberty and insulin resistance. Treatment with gonadotropin-releasing hormone analogues can delay progression of central puberty and preserve adult height potential. Long-term follow up is essential to determine the natural history and optimal management in adulthood.
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http://dx.doi.org/10.1038/nrendo.2016.138DOI Listing
February 2017