Publications by authors named "Christina Evers"

30 Publications

  • Page 1 of 1

The Frog as a Model to Study Joubert Syndrome: The Case of a Human Patient With Compound Heterozygous Variants in .

Front Physiol 2019 25;10:134. Epub 2019 Feb 25.

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

Joubert syndrome (JS) is a congenital autosomal-recessive or-in rare cases-X-linked inherited disease. The diagnostic hallmark of the so-called molar tooth sign describes the morphological manifestation of the mid- and hind-brain in axial brain scans. Affected individuals show delayed development, intellectual disability, ataxia, hyperpnea, sleep apnea, abnormal eye, and tongue movements as well as hypotonia. At the cellular level, JS is associated with the compromised biogenesis of sensory cilia, which identifies JS as a member of the large group of ciliopathies. Here we report on the identification of novel compound heterozygous variants (p.Y503C and p.Q485) in the centrosomal gene in a patient with JS via trio whole exome sequencing. We have studied the underlying disease mechanism in the frog , which offers fast assessment of cilia functions in a number of embryological contexts. Morpholino oligomer (MO) mediated knockdown of the orthologous gene resulted in defective mucociliary clearance in the larval epidermis, due to reduced cilia numbers and motility on multiciliated cells. To functionally assess patient alleles, mutations were analyzed in the larval skin: the p.Q485 nonsense mutation resulted in a disturbed localization of PIBF1 to the ciliary base. This mutant failed to rescue the ciliation phenotype following knockdown of endogenous . In contrast, the missense variant p.Y503C resulted in attenuated rescue capacity compared to the wild type allele. Based on these results, we conclude that in the case of this patient, JS is the result of a pathogenic combination of an amorphic and a hypomorphic allele. Our study underscores the versatility of the model to study ciliopathies such as JS in a rapid and cost-effective manner, which should render this animal model attractive for future studies of human ciliopathies.
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http://dx.doi.org/10.3389/fphys.2019.00134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6397843PMC
February 2019

Characterization of glycosylphosphatidylinositol biosynthesis defects by clinical features, flow cytometry, and automated image analysis.

Genome Med 2018 01 9;10(1). Epub 2018 Jan 9.

The Jackson Laboratory for Genomic Medicine, 06032, Farmington, USA.

Background: Glycosylphosphatidylinositol biosynthesis defects (GPIBDs) cause a group of phenotypically overlapping recessive syndromes with intellectual disability, for which pathogenic mutations have been described in 16 genes of the corresponding molecular pathway. An elevated serum activity of alkaline phosphatase (AP), a GPI-linked enzyme, has been used to assign GPIBDs to the phenotypic series of hyperphosphatasia with mental retardation syndrome (HPMRS) and to distinguish them from another subset of GPIBDs, termed multiple congenital anomalies hypotonia seizures syndrome (MCAHS). However, the increasing number of individuals with a GPIBD shows that hyperphosphatasia is a variable feature that is not ideal for a clinical classification.

Methods: We studied the discriminatory power of multiple GPI-linked substrates that were assessed by flow cytometry in blood cells and fibroblasts of 39 and 14 individuals with a GPIBD, respectively. On the phenotypic level, we evaluated the frequency of occurrence of clinical symptoms and analyzed the performance of computer-assisted image analysis of the facial gestalt in 91 individuals.

Results: We found that certain malformations such as Morbus Hirschsprung and diaphragmatic defects are more likely to be associated with particular gene defects (PIGV, PGAP3, PIGN). However, especially at the severe end of the clinical spectrum of HPMRS, there is a high phenotypic overlap with MCAHS. Elevation of AP has also been documented in some of the individuals with MCAHS, namely those with PIGA mutations. Although the impairment of GPI-linked substrates is supposed to play the key role in the pathophysiology of GPIBDs, we could not observe gene-specific profiles for flow cytometric markers or a correlation between their cell surface levels and the severity of the phenotype. In contrast, it was facial recognition software that achieved the highest accuracy in predicting the disease-causing gene in a GPIBD.

Conclusions: Due to the overlapping clinical spectrum of both HPMRS and MCAHS in the majority of affected individuals, the elevation of AP and the reduced surface levels of GPI-linked markers in both groups, a common classification as GPIBDs is recommended. The effectiveness of computer-assisted gestalt analysis for the correct gene inference in a GPIBD and probably beyond is remarkable and illustrates how the information contained in human faces is pivotal in the delineation of genetic entities.
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http://dx.doi.org/10.1186/s13073-017-0510-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5759841PMC
January 2018

Impact of clinical exomes in neurodevelopmental and neurometabolic disorders.

Mol Genet Metab 2017 08 30;121(4):297-307. Epub 2017 Jun 30.

Institute of Human Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.

Whole exome sequencing (WES) is well established in research and is now being introduced into clinically indicated diagnostics (so-called clinical exomes). We evaluated the diagnostic yield and clinical implications of WES in 72 patients from 60 families with undiagnosed neurodevelopmental disorders (NDD), neurometabolic disorders, and dystonias. Pathogenic or likely pathogenic variants leading to a molecular diagnosis could be identified in 21 of the 60 families (overall 35%, in 36% of patients with NDD, in 43% of patients with neurometabolic disorders, in 25% of patients with dystonias). In one family two coexisting autosomal recessive diseases caused by homozygous pathogenic variants in two different genes were diagnosed. In another family, a homozygous frameshift variant in STRADA was found to cause a severe NDD with early onset epilepsy, brain anomalies, hypotonia, heart defect, nephrocalcinosis, macrocephaly and distinctive facies so far designated as PMSE (polyhydramnios, megalencephaly, symptomatic epilepsy) syndrome. In 7 of the 21 families with a molecular diagnosis the pathogenic variants were only identified by clinical follow-up, manual reevaluation of the literature, a change of filter setting, and/or reconsideration of inheritance pattern. Most importantly, clinical implications included management changes in 8 cases and impact on family planning in 20 families with a molecular diagnosis. This study shows that reevaluation and follow-up can improve the diagnostic rate and that WES results have important implications on medical management and family planning. Furthermore, we could confirm STRADA as a gene associated with syndromic ID but find it questionable if the current designation as PMSE depicts the most important clinical features.
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http://dx.doi.org/10.1016/j.ymgme.2017.06.014DOI Listing
August 2017

Expanding Phenotype of De Novo Mutations in GNAO1: Four New Cases and Review of Literature.

Neuropediatrics 2017 10 19;48(5):371-377. Epub 2017 Jun 19.

Department of Neuropediatrics and Muscle Disorders, Medical Center, University of Freiburg, Freiburg, Germany.

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http://dx.doi.org/10.1055/s-0037-1603977DOI Listing
October 2017

Familial breast cancer: Genetic counseling over time, including patients´ expectations and initiators considering the Angelina Jolie effect.

PLoS One 2017 25;12(5):e0177893. Epub 2017 May 25.

Department of Gynecology and Obstetrics, University Hospital Heidelberg, Heidelberg, Germany.

Purpose: The German Consortium for hereditary breast/ovarian cancer (GC-HBOC) aims for nationwide access to professional, individualized yet structured care for families at high risk. The identification of such families remains key for optimal care. Our study evaluates counselees' characteristics, referral practices, expectations and motivations in respect to their first genetic consultation. The impact of the Angelina Jolie Effect (AJE) was prospectively assessed.

Methods: All counselees could participate through a questionnaire. Groups were built in respect to neoadjuvant chemotherapy (FT) and before/after AJE.

Results: The 917 (88.5%) counselees (FT: 8.2%) were on average female (97.3%), with a mean age of 44.6, had children (71.9%), higher education (88%), personal (46.4%) or at least one first-degree relative (74.6%) with BC/OC or known BRCA1/2 mutation (11.8%), were in a relationship (76.1%), and living in a village (40.7%). The AJE is associated with significantly fewer cancelations (p = 0.005), more attendance among men (4.2% vs. 0.8%, p = 0.002), and people with familial BRCA1/2 (14.8% vs. 7.5%, p = 0.003). The majority seek information regarding their cancer risk (83%) or relatives' risk (74.8%), HBOC (69.1%), and surveillance programs for themselves (66.6%) or relatives (60.6%).

Conclusion: Enhanced media awareness of genetic cancer motivates patients, including other patient groups. A higher number of participants, including more men, are attending GC due to the AJE. In terms of the rising complexity of genetic testing, the analysis of patients' expectations and initiators for GC suggests that there is an urgent need to develop to participate motivation analysis. The factors revealed as impediments to accessing GC-HBOC guide recommendations to optimize access to genetic counseling. Medical educational programs for primary gynecologists and families at risk might be options to reach more participants.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0177893PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5444628PMC
September 2017

Diagnosis of CoPAN by whole exome sequencing: Waking up a sleeping tiger's eye.

Am J Med Genet A 2017 Jul 10;173(7):1878-1886. Epub 2017 May 10.

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

Neurodegeneration with brain iron accumulation (NBIA) is a group of neurodegenerative disorders characterized by iron accumulation in the basal ganglia. Recently, mutations in CoA synthase (COASY) have been identified as a cause of a novel NBIA subtype (COASY Protein-Associated Neurodegeneration, CoPAN) in two patients with dystonic paraparesis, parkinsonian features, cognitive impairment, behavior abnormalities, and axonal neuropathy. COASY encodes an enzyme required for Coenzyme A (CoA) biosynthesis. Using whole exome sequencing (WES) we identified compound heterozygous COASY mutations in two siblings with intellectual disability, ataxic gait, progressive spasticity, and obsessive-compulsive behavior. The "eye-of-the tiger-sign," a characteristic hypointense spot within the hyperintense globi pallidi on MRI found in the most common subtype of NBIA (Pantothenate Kinase-Associated Neurodegeneration, PKAN), was not present. Instead, bilateral hyperintensity and swelling of caudate nucleus, putamen, and thalamus were found. In addition, our patients showed a small corpus callosum and frontotemporal and parietal white matter changes, expanding the brain phenotype of patients with CoPAN. Metabolic investigations showed increased free carnitine and decreased acylcarnitines in the patientś dried blood samples. Carnitine palmitoyl transferase 1 (CPT1) deficiency was excluded by further enzymatic and metabolic investigations. As CoA and its derivate Acetyl-CoA play an essential role in fatty acid metabolism, we assume that abnormal acylcarnitine profiles are a result of the COASY mutations. This report not only illustrates that WES is a powerful tool to elucidate the etiology of rare genetic diseases, but also identifies unique neuroimaging and metabolic findings that may be key features for an early diagnosis of CoPAN.
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http://dx.doi.org/10.1002/ajmg.a.38252DOI Listing
July 2017

Women at familial risk of breast cancer electing for prophylactic mastectomy: frequencies, procedures, and decision-making characteristics.

Arch Gynecol Obstet 2017 Jun 24;295(6):1451-1458. Epub 2017 Apr 24.

Department of Obstetrics and Gynaecology, University Hospital Heidelberg, Im Neuenheimer Feld 440, 69120, Heidelberg, Germany.

Background: Some women of families at high risk of breast cancer (BC) choose prophylactic mastectomy (PM) in spite of ambiguous evidence for survival benefits. The aim of this study was to investigate counselees' characteristics, decisions on PM, and frequencies of different procedures to better understand how to tailor interventions.

Patients And Methods: Eight hundred and forty-nine counselees who attended interdisciplinary consultation for genetic risk adjustment at the University Hospital Heidelberg between July 2009 and July 2011 received a tripartite questionnaire addressing sociodemographic characteristics, psychological parameters, behavioural questions, and medical data.

Results: Six hundred and twelve of the 849 counselees (72%) returned the questionnaire. Four hundred were classified as high risk of genetic BC (19.5% BRCA mutation carriers; 4% unclassified variant (UV); and 76.5% calculated as high risk by pedigree). Two hundred and thirteen out of 400 (53%) were diagnosed with BC. Fourteen out of 54 (27%) BRCA mutation carriers with BC chose contralateral PM (CPM) compared to 24/126 (14%) without a mutation but with a personal BC history (p = 0.2175). Of those without BC, 12/27 (44%) mutation carriers opted for bilateral PM (BPM) compared to none without a mutation (p < 0.0001). Women who received any PM (CPM and BPM) reported a higher emotional burden from partners (p = 0.003) and family (p = 0.008), more worries regarding children and family (p = 0.003) and were associated with positive mutation status and higher heterozygous and lifetime risk (all p < 0.001).

Conclusion: Although evidence on survival benefit is unclear in several clinical situations, a relevant number of counselees opt for PM. Counselees may decide based on other reasons than survival benefit.
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http://dx.doi.org/10.1007/s00404-017-4376-yDOI Listing
June 2017

DDX3X mutations in two girls with a phenotype overlapping Toriello-Carey syndrome.

Am J Med Genet A 2017 May 29;173(5):1369-1373. Epub 2017 Mar 29.

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

Recently, de novo heterozygous variants in DDX3X have been reported in about 1.5% of 2659 females with previously unexplained intellectual disability (ID). We report on the identification of DDX3X variants in two unrelated girls with clinical features of Toriello-Carey Syndrome (T-CS). In patient 1, the recurrent variant c.1703C>T; p.(P568L) was identified when reconsidering X-linked de novo heterozygous variants in exome sequencing data. In patient 2, the DDX3X variant c.1600C>G; p.(R534G) was also detected by exome sequencing. Based on these data, de novo heterozygous DDX3X variants should be considered not only in females with unexplained ID, but also in individuals with a clinical diagnosis of T-CS.
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http://dx.doi.org/10.1002/ajmg.a.38164DOI Listing
May 2017

Genotype and phenotype in patients with Noonan syndrome and a RIT1 mutation.

Genet Med 2016 12 21;18(12):1226-1234. Epub 2016 Apr 21.

Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany.

Purpose: Noonan syndrome (NS) is an autosomal-dominant disorder characterized by craniofacial dysmorphism, growth retardation, cardiac abnormalities, and learning difficulties. It belongs to the RASopathies, which are caused by germ-line mutations in genes encoding components of the RAS mitogen-activated protein kinase (MAPK) pathway. RIT1 was recently reported as a disease gene for NS, but the number of published cases is still limited.

Methods: We sequenced RIT1 in 310 mutation-negative individuals with a suspected RASopathy and prospectively in individuals who underwent genetic testing for NS. Using a standardized form, we recorded clinical features of all RIT1 mutation-positive patients. Clinical and genotype data from 36 individuals with RIT1 mutation reported previously were reviewed.

Results: Eleven different RIT1 missense mutations, three of which were novel, were identified in 33 subjects from 28 families; codons 57, 82, and 95 represent mutation hotspots. In relation to NS of other genetic etiologies, prenatal abnormalities, cardiovascular disease, and lymphatic abnormalities were common in individuals with RIT1 mutation, whereas short stature, intellectual problems, pectus anomalies, and ectodermal findings were less frequent.

Conclusion: RIT1 is one of the major genes for NS. The RIT1-associated phenotype differs gradually from other NS subtypes, with a high prevalence of cardiovascular manifestations, especially hypertrophic cardiomyopathy, and lymphatic problems.Genet Med 18 12, 1226-1234.
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http://dx.doi.org/10.1038/gim.2016.32DOI Listing
December 2016

Exome sequencing reveals a novel CWF19L1 mutation associated with intellectual disability and cerebellar atrophy.

Am J Med Genet A 2016 06 26;170(6):1502-9. Epub 2016 Mar 26.

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

Intellectual disability (ID) with cerebellar ataxia comprises a genetically heterogeneous group of neurodevelopmental disorders. We identified a homozygous frameshift mutation in CWF19L1 (c.467delC; p.(P156Hfs*33)) by a combination of linkage analysis and Whole Exome Sequencing in a consanguineous Turkish family with a 9-year-old boy affected by early onset cerebellar ataxia and mild ID. Serial MRI showed mildly progressive cerebellar atrophy. Absent C19L1 protein expression in lymphoblastoid cell lines strongly suggested that c.467delC is a disease-causing alteration. One further pregnancy of the mother had been terminated at 22 weeks of gestation because of a small cerebellum and agenesis of corpus callosum. The homozygous CWF19L1 variant was also present in the fetus. Postmortem examination of the fetus in addition showed unilateral hexadactyly and vertebral malformations. These features have not been reported and may represent an expansion of the CWF19L1-related phenotypic spectrum, but could also be due to another, possibly autosomal recessive disorder. The exact function of the evolutionarily highly conserved C19L1 protein is unknown. So far, homozygous or compound heterozygous mutations in CWF19L1 have been identified in two Turkish siblings and a Dutch girl, respectively, affected by cerebellar ataxia and ID. A zebrafish model showed that CWF19L1 loss-of-function mutations result in abnormal cerebellar morphology and movement disorders. Our report corroborates that loss-of-function mutations in CWF19Ll lead to early onset cerebellar ataxia and (progressive) cerebellar atrophy. © 2016 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/ajmg.a.37632DOI Listing
June 2016

Adherence to the breast cancer surveillance program for women at risk for familial breast and ovarian cancer versus overscreening: a monocenter study in Germany.

Breast Cancer Res Treat 2016 Apr 9;156(2):289-99. Epub 2016 Mar 9.

Department of Obstetrics and Gynecology, University Hospital Heidelberg, Im Neuenheimer Feld 440, 69120, Heidelberg, Germany.

Breast cancer (BC) is the leading cancer among women worldwide and in 5-10 % of cases is of hereditary origin, mainly due to BRCA1/2 mutations. Therefore, the German Consortium for Familial Breast and Ovarian Cancer (HBOC) with its 15 specialized academic centers offers families at high risk for familial/hereditary cancer a multimodal breast cancer surveillance program (MBCS) with regular breast MRI, mammography, ultrasound, and palpation. So far, we know a lot about the psychological effects of genetic testing, but we know little about risk-correlated adherence to MBCS or prophylactic surgery over time. The aim of this study was to investigate counselees' adherence to recommendations for MBCS in order to adjust the care supply and define predictors for incompliance. All counselees, who attended HBOC consultation at the University Hospital Heidelberg between July 01, 2009 and July 01, 2011 were eligible to participate. A tripartite questionnaire containing sociodemographic information, psychological parameters, behavioral questions, and medical data collection from the German consortium were used. A high participation rate was achieved among the study population, with 72 % returning the questionnaire. This study showed a rate of 59 % of full-adherers to the MBCS. Significant predictors for partial or full adherence were having children (p = 0.0221), younger daughters (p = 0.01795), a higher awareness of the topic HBOC (p = 0.01795, p < 0.0001), a higher perceived breast cancer risk (p < 0.0001), and worries (p = 0.0008)/impairment (p = 0.0257) by it. Although the current data suggest a good adherence of MBCS, prospective studies are needed to understand counselees' needs to further improve surveillance programs and adherence to them. Adherence to the breast cancer surveillance program for women at risk for familial breast and ovarian cancer versus overscreening-a monocenter study in Germany.
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http://dx.doi.org/10.1007/s10549-016-3748-5DOI Listing
April 2016

Phenotypic and molecular insights into CASK-related disorders in males.

Orphanet J Rare Dis 2015 Apr 12;10:44. Epub 2015 Apr 12.

Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.

Background: Heterozygous loss-of-function mutations in the X-linked CASK gene cause progressive microcephaly with pontine and cerebellar hypoplasia (MICPCH) and severe intellectual disability (ID) in females. Different CASK mutations have also been reported in males. The associated phenotypes range from nonsyndromic ID to Ohtahara syndrome with cerebellar hypoplasia. However, the phenotypic spectrum in males has not been systematically evaluated to date.

Methods: We identified a CASK alteration in 8 novel unrelated male patients by targeted Sanger sequencing, copy number analysis (MLPA and/or FISH) and array CGH. CASK transcripts were investigated by RT-PCR followed by sequencing. Immunoblotting was used to detect CASK protein in patient-derived cells. The clinical phenotype and natural history of the 8 patients and 28 CASK-mutation positive males reported previously were reviewed and correlated with available molecular data.

Results: CASK alterations include one nonsense mutation, one 5-bp deletion, one mutation of the start codon, and five partial gene deletions and duplications; seven were de novo, including three somatic mosaicisms, and one was familial. In three subjects, specific mRNA junction fragments indicated in tandem duplication of CASK exons disrupting the integrity of the gene. The 5-bp deletion resulted in multiple aberrant CASK mRNAs. In fibroblasts from patients with a CASK loss-of-function mutation, no CASK protein could be detected. Individuals who are mosaic for a severe CASK mutation or carry a hypomorphic mutation still showed detectable amount of protein.

Conclusions: Based on eight novel patients and all CASK-mutation positive males reported previously three phenotypic groups can be distinguished that represent a clinical continuum: (i) MICPCH with severe epileptic encephalopathy caused by hemizygous loss-of-function mutations, (ii) MICPCH associated with inactivating alterations in the mosaic state or a partly penetrant mutation, and (iii) syndromic/nonsyndromic mild to severe ID with or without nystagmus caused by CASK missense and splice mutations that leave the CASK protein intact but likely alter its function or reduce the amount of normal protein. Our findings facilitate focused testing of the CASK gene and interpreting sequence variants identified by next-generation sequencing in cases with a phenotype resembling either of the three groups.
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http://dx.doi.org/10.1186/s13023-015-0256-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4449965PMC
April 2015

Mutations in a TGF-β ligand, TGFB3, cause syndromic aortic aneurysms and dissections.

J Am Coll Cardiol 2015 Apr;65(13):1324-1336

Department of Cardiology, University Hospital Antwerp, Antwerp, Belgium.

Background: Aneurysms affecting the aorta are a common condition associated with high mortality as a result of aortic dissection or rupture. Investigations of the pathogenic mechanisms involved in syndromic types of thoracic aortic aneurysms, such as Marfan and Loeys-Dietz syndromes, have revealed an important contribution of disturbed transforming growth factor (TGF)-β signaling.

Objectives: This study sought to discover a novel gene causing syndromic aortic aneurysms in order to unravel the underlying pathogenesis.

Methods: We combined genome-wide linkage analysis, exome sequencing, and candidate gene Sanger sequencing in a total of 470 index cases with thoracic aortic aneurysms. Extensive cardiological examination, including physical examination, electrocardiography, and transthoracic echocardiography was performed. In adults, imaging of the entire aorta using computed tomography or magnetic resonance imaging was done.

Results: Here, we report on 43 patients from 11 families with syndromic presentations of aortic aneurysms caused by TGFB3 mutations. We demonstrate that TGFB3 mutations are associated with significant cardiovascular involvement, including thoracic/abdominal aortic aneurysm and dissection, and mitral valve disease. Other systemic features overlap clinically with Loeys-Dietz, Shprintzen-Goldberg, and Marfan syndromes, including cleft palate, bifid uvula, skeletal overgrowth, cervical spine instability and clubfoot deformity. In line with previous observations in aortic wall tissues of patients with mutations in effectors of TGF-β signaling (TGFBR1/2, SMAD3, and TGFB2), we confirm a paradoxical up-regulation of both canonical and noncanonical TGF-β signaling in association with up-regulation of the expression of TGF-β ligands.

Conclusions: Our findings emphasize the broad clinical variability associated with TGFB3 mutations and highlight the importance of early recognition of the disease because of high cardiovascular risk.
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http://dx.doi.org/10.1016/j.jacc.2015.01.040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4380321PMC
April 2015

SIPA1L3 identified by linkage analysis and whole-exome sequencing as a novel gene for autosomal recessive congenital cataract.

Eur J Hum Genet 2015 Dec 25;23(12):1627-33. Epub 2015 Mar 25.

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

Congenital cataract (CC) is one of the most important causes for blindness or visual impairment in infancy. A substantial proportion of isolated CCs has monogenic causes. The disease is genetically heterogeneous, and all Mendelian modes of inheritance have been reported. We mapped a locus for isolated CC on 19p13.1-q13.2 in a distantly consanguineous German family with two sisters affected by dense white cataracts. Whole-exome sequencing identified a homozygous nonsense variant c.4489C>T (p.(R1497*)) in SIPA1L3 (signal-induced proliferation-associated 1 like 3) in both affected children. SIPA1L3 encodes a GTPase-activating protein (GAP), which interacts with small GTPases of the Rap family via its Rap-GAP-domain. The suggested role of Rap GTPases in cell growth, differentiation and organization of the cytoskeleton in the human lens, and lens-enriched expression of the murine ortholog gene Sipa1l3 in embryonic mice indicates that this gene is crucial for early lens development. Our results provide evidence that sequence variants in human SIPA1L3 cause autosomal recessive isolated CC and give new insight into the molecular pathogenesis underlying human cataracts.
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http://dx.doi.org/10.1038/ejhg.2015.46DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4795213PMC
December 2015

Duplication Xp11.22-p14 in females: does X-inactivation help in assessing their significance?

Am J Med Genet A 2015 Mar;167A(3):553-62

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

In females, large duplications in Xp often lead to preferential inactivation of the aberrant X chromosome and a normal phenotype. Recently, a recurrent ∼4.5 Mb microduplication of Xp11.22-p11.23 was found in females with developmental delay/intellectual disability and other neurodevelopmental disorders (speech development disorder, epilepsy or EEG anomalies, autism spectrum disorder, or behavioral disorder). Unexpectedly, most of them showed preferential inactivation of the normal X chromosome. We describe five female patients carrying de novo Xp duplications encompassing p11.23. Patient 1 carried the recurrent microduplication Xp11.22-p11.23, her phenotype and X-chromosome inactivation (XI) pattern was consistent with previous reports. The other four patients had novel Xp duplications. Two were monozygotic twins with a similar phenotype to Patient 1 and unfavorable XI skewing carrying an overlapping ∼5 Mb duplication of Xp11.23-p11.3. Patient 4 showed a duplication of ∼5.5 Mb comparable to the twins but had a more severe phenotype and unskewed XI. Patient 5 had a ∼8.5 Mb duplication Xp11.23-p11.4 and presented with mild ID, epilepsy, behavioral problems, and inconsistent results of XI analysis. A comparison of phenotype, size and location of the duplications and XI patterns in Patients 1-5 and previously reported females with overlapping duplications provides further evidence that microduplications encompassing Xp11.23 are associated with ID and other neurodevelopmental disorders in females. To further assess the implication of XI for female carriers, we recommend systematic analysis of XI pattern in any female with X imbalances that are known or suspected to be pathogenic.
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http://dx.doi.org/10.1002/ajmg.a.36897DOI Listing
March 2015

Next-generation sequencing in X-linked intellectual disability.

Eur J Hum Genet 2015 Nov 4;23(11):1513-8. Epub 2015 Feb 4.

Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany.

X-linked intellectual disability (XLID) is a genetically heterogeneous disorder with more than 100 genes known to date. Most genes are responsible for a small proportion of patients only, which has hitherto hampered the systematic screening of large patient cohorts. We performed targeted enrichment and next-generation sequencing of 107 XLID genes in a cohort of 150 male patients. Hundred patients had sporadic intellectual disability, and 50 patients had a family history suggestive of XLID. We also analysed a sporadic female patient with severe ID and epilepsy because she had strongly skewed X-inactivation. Target enrichment and high parallel sequencing allowed a diagnostic coverage of >10 reads for ~96% of all coding bases of the XLID genes at a mean coverage of 124 reads. We found 18 pathogenic variants in 13 XLID genes (AP1S2, ATRX, CUL4B, DLG3, IQSEC2, KDM5C, MED12, OPHN1, SLC9A6, SMC1A, UBE2A, UPF3B and ZDHHC9) among the 150 male patients. Thirteen pathogenic variants were present in the group of 50 familial patients (26%), and 5 pathogenic variants among the 100 sporadic patients (5%). Systematic gene dosage analysis for low coverage exons detected one pathogenic hemizygous deletion. An IQSEC2 nonsense variant was detected in the female ID patient, providing further evidence for a role of this gene in encephalopathy in females. Skewed X-inactivation was more frequently observed in mothers with pathogenic variants compared with those without known X-linked defects. The mutation rate in the cohort of sporadic patients corroborates previous estimates of 5-10% for X-chromosomal defects in male ID patients.
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http://dx.doi.org/10.1038/ejhg.2015.5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4613482PMC
November 2015

The "Wagshurst study": p.Val40Ile transthyretin gene variant causes late-onset cardiomyopathy.

Amyloid 2014 Dec 7;21(4):267-75. Epub 2014 Oct 7.

Department of Cardiology, Angiology, and Respiratory Medicine, University Hospital Heidelberg , Heidelberg , Germany .

Background: Transthyretin-related amyloidosis (ATTR) is characterized by a wide heterogeneity of genotypes and predominantly neurological and cardiac phenotypes. This study aims to characterize a cohort of patients with the rare transthyretin (TTR) Val20Ile (p.TTRVal40Ile) variant.

Methods And Results: This study comprises a single-center cohort of 59 individuals subsequently evaluated for TTRVal20Ile variant due to clinical (n = 13) or predictive (n = 46) reasons. All patients were mainly related to Wagshurst, a small village in the South of Germany. Clinical assessment was performed by neurological evaluation, echocardiography, electrocardiography, cardiac biomarkers, cardiac MRI (n = 13), and (99m)Tc-DPD scintigraphy (n = 16). The rare TTRVal20Ile variant was found in 41 patients; evidence of cardiac amyloidosis was present in 22 patients. Evidence of pulmonary involvement was obtained by (99m)Tc-DPD scintigraphy in eight patients. No further organ involvement was observed in any of the patients carrying TTRVal20Ile variant. Correlation of inter-ventricular septum thickness as well as decrease of left ventricular longitudinal contractility with age was observed. Moreover, thickness of inter-ventricular septum correlated with NT-proBNP plasma levels and decrease in mitral annular plane systolic excursion. Cardiac manifestation started during the early sixth life decade indicated by higher left ventricular septum thickness and NT-proBNP plasma levels as compared to patients in fifth decade of life. All patients of the seventh and eighth life decade (n = 10) presented with cardiac amyloidosis. During median follow-up of 26 (0-108) months, eight patients underwent heart transplantation with 1-year mortality rate of 25%.

Conclusions: This large cohort of individuals carrying the TTRVal20Ile mutation reveals a predominantly cardiac phenotype with high penetrance and late onset of symptoms. Cardiac manifestation progressed to end-stage heart failure within a few years, finally requiring heart transplantation with promising long-term survival rates.
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http://dx.doi.org/10.3109/13506129.2014.967846DOI Listing
December 2014

Mosaic deletion of EXOC6B: further evidence for an important role of the exocyst complex in the pathogenesis of intellectual disability.

Am J Med Genet A 2014 Dec 24;164A(12):3088-94. Epub 2014 Sep 24.

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

We describe a boy with developmental delay, speech delay, and minor dysmorphic features with a heterozygous de novo ∼460 kb deletion at 2p13.2 involving only parts of EXOC6B present in about 50% of lymphocytes. This widely expressed gene encodes the exocyst component 6B, which is part of a multiprotein complex required for targeted exocytosis. Little is known about the effect of EXOC6B haploinsufficiency. In 2008, a patient with a complex syndromic phenotype, including left renal agenesis, neutropenia, recurrent pulmonary infections, long bone diaphysis broadening, growth retardation, and developmental delay (DD) was found to carry a de novo translocation t(2;7) involving TSN3 and EXOC6B. Further characterization of the translocation indicated that disruption of TSN3 may be responsible for the skeletal phenotype. Recently, a heterozygous deletion of EXOC6B along with a deletion of the CYP26B1 gene has been reported in a boy with intellectual disability, speech delay, hyperactivity, facial asymmetry, a dysplastic ear, brachycephaly, and mild joint contractures. Additionally, disruption of EXOC6B by a de novo balanced translocation t(2;8) has been described in a patient with developmental delay, epilepsy, autistic and aggressive behavior. This is the first report of a de novo deletion affecting only EXOC6B in an individual with developmental delay. In conclusion, based on our findings and recent data from the literature, there is evidence that EXOC6B and the exocyst complex might play an important role in the molecular pathogenesis of intellectual disability.
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http://dx.doi.org/10.1002/ajmg.a.36770DOI Listing
December 2014

Central 22q11.2 deletions.

Am J Med Genet A 2014 Nov 14;164A(11):2707-23. Epub 2014 Aug 14.

University of Groningen, University Medical Centre Groningen, Department of Genetics, Groningen, The Netherlands.

22q11.2 deletion syndrome is one of the most common microdeletion syndromes. Most patients have a deletion resulting from a recombination of low copy repeat blocks LCR22-A and LCR22-D. Loss of the TBX1 gene is considered the most important cause of the phenotype. A limited number of patients with smaller, overlapping deletions distal to the TBX1 locus have been described in the literature. In these patients, the CRKL gene is deleted. Haploinsufficiency of this gene has also been implicated in the pathogenesis of 22q11.2 deletion syndrome. To distinguish these deletions (comprising the LCR22-B to LCR22-D region) from the more distal 22q11.2 deletions (located beyond LCR22-D), we propose the term "central 22q11.2 deletions". In the present study we report on 27 new patients with such a deletion. Together with information on previously published cases, we review the clinical findings of 52 patients. The prevalence of congenital heart anomalies and the frequency of de novo deletions in patients with a central deletion are substantially lower than in patients with a common or distal 22q11.2 deletion. Renal and urinary tract malformations, developmental delays, cognitive impairments and behavioral problems seem to be equally frequent as in patients with a common deletion. None of the patients had a cleft palate. Patients with a deletion that also encompassed the MAPK1 gene, located just distal to LCR22-D, have a different and more severe phenotype, characterized by a higher prevalence of congenital heart anomalies, growth restriction and microcephaly. Our results further elucidate genotype-phenotype correlations in 22q11.2 deletion syndrome spectrum.
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http://dx.doi.org/10.1002/ajmg.a.36711DOI Listing
November 2014

Clinical and molecular characterization of the BRCA2 p.Asn3124Ile variant reveals substantial evidence for pathogenic significance.

Breast Cancer Res Treat 2014 Jun 12;145(2):451-60. Epub 2014 Apr 12.

Division Molecular Biology of Breast Cancer, Department of Gynecology and Obstetrics, University of Heidelberg, Im Neuenheimer Feld 440, 69120, Heidelberg, Germany,

Variants of uncertain clinical significance (VUS) in the high-penetrance breast cancer susceptibility genes BRCA1 and BRCA2 represent a major obstacle in genetic counseling of high-risk breast cancer families. We analyzed a missense VUS located in BRCA2 (p.Asn3124Ile; HGVS: BRCA2 c.9371A > T) present in seven independent high-risk breast cancer families that were counseled and genetically tested in South-West Germany. The VUS was identified by DNA sequencing. We analyzed co-occurrence with deleterious BRCA1/2 mutations, segregation, evolutionary conservation, in silico impact prediction, and prevalence in the general population. All carriers of the VUS suffered from breast or ovarian cancer. In two families, an additional high burden of other cancers such as pancreatic, prostate, and gastric cancers was reported, one further family included two cases of male breast cancer. The VUS did not co-occur with deleterious BRCA1/2 mutations and segregated in two affected individuals of one family. In contrast to the 7/1,347 (0,5 %) tested high-risk BC families without clearly pathogenic mutations in BRCA1/2, none of 3,126 healthy population controls sharing the same ethnic and geographical background were found to carry this VUS (p = 0.0002). In-silico prediction revealed strong evolutionary conservation of the asparagine residue, residing in the C-terminal oligonucleotide-binding-fold-3 region, and a most likely damaging impact of this exchange on the protein structure. The BRCA2 p.Asn3124Ile (BRCA2 c.9371A > T) variant is a rare mutation with a damaging effect on the BRCA2 protein that is strongly associated with familial breast and ovarian cancer risk, indicating its most likely pathogenic nature and clinical relevance.
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http://dx.doi.org/10.1007/s10549-014-2943-5DOI Listing
June 2014

Novel mutations including deletions of the entire OFD1 gene in 30 families with type 1 orofaciodigital syndrome: a study of the extensive clinical variability.

Hum Mutat 2013 Jan 17;34(1):237-47. Epub 2012 Oct 17.

Institute of Human Genetics, University Clinic Freiburg, Freiburg, Germany.

OFD1, now recognized as a ciliopathy, is characterized by malformations of the face, oral cavity and digits, and is transmitted as an X-linked condition with lethality in males. Mutations in OFD1 also cause X-linked Joubert syndrome (JBTS10) and Simpson-Golabi-Behmel syndrome type 2 (SGBS2). We have studied 55 sporadic and six familial cases of suspected OFD1. Comprehensive mutation analysis in OFD1 revealed mutations in 37 female patients from 30 families; 22 mutations have not been previously described including two heterozygous deletions spanning OFD1 and neighbouring genes. Analysis of clinical findings in patients with mutations revealed that oral features are the most reliable diagnostic criteria. A first, detailed evaluation of brain MRIs from seven patients with cognitive defects illustrated extensive variability with the complete brain phenotype consisting of complete agenesis of the corpus callosum, large single or multiple interhemispheric cysts, striking cortical infolding of gyri, ventriculomegaly, mild molar tooth malformation and moderate to severe cerebellar vermis hypoplasia. Although the OFD1 gene apparently escapes X-inactivation, skewed inactivation was observed in seven of 14 patients. The direction of skewing did not correlate with disease severity, reinforcing the hypothesis that additional factors contribute to the extensive intrafamilial variability.
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http://dx.doi.org/10.1002/humu.22224DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5497464PMC
January 2013

Integrated multiplex ligation dependent probe amplification (MLPA) assays for the detection of alterations in the HEXB, GM2A and SMARCAL1 genes to support the diagnosis of Morbus Sandhoff, M. Tay-Sachs variant AB and Schimke immuno-osseous dysplasia in humans.

Mol Cell Probes 2013 Feb 27;27(1):32-7. Epub 2012 Aug 27.

Human Genetics, Ruhr University Bochum, Universitaetsstrasse 150, 44801 Bochum, Germany.

Multiplex ligation dependent probe amplification (MLPA) assays were designed for the genes HEXB (OMIM: 606873), GM2A (OMIM: 613109) and SMARCAL1 (OMIM: 606622) of humans. Two sets of synthetic MLPA probes for these coding exons were tested. Changes in copy numbers were detected as well as single nucleotide polymorphisms (SNPs) by complementary DNA sequence analyses. The MLPA method was shown to be reliable for mutation detection and identified five published and 12 new mutations. In all cases from a Morbus Sandhoff cohort of patients, exclusively one variation in copy number was observed and linked to a nucleotide alteration called c.1614-14C>A. This deletion comprised exons 1-5. One of these cases is described in detail. Deletions were neither detected in the GM2A nor the SMARCAL1 genes. The MLPA assays complement routine diagnostics for M. Sandhoff (OMIM: 268800), M. Tay-Sachs variant AB (OMIM: 272750) and Schimke immuno-osseous dysplasia (OMIM: 242900).
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http://dx.doi.org/10.1016/j.mcp.2012.08.007DOI Listing
February 2013

Hepatoblastoma in two siblings and familial adenomatous polyposis: causal nexus or coincidence?

Fam Cancer 2012 Sep;11(3):529-33

Institute of Human Genetics, Heidelberg University, Im Neuenheimer Feld 366, 69120, Heidelberg, Germany.

Infantile and childhood hepatoblastoma (HB) occurs more frequently in children with hereditary predisposition to familial adenomatous polyposis (FAP) than in the general population. The occurrence of HB in two infant siblings is reported. The sister died of the disease. The brother survived the HB and was later diagnosed with familial adenomatous polyposis and advanced rectal cancer. He was found to carry a germline mutation of the APC gene. Presuming that the HB in the two siblings was the first manifestation of FAP we performed APC mutation analysis in DNA from archived tumour tissue of his sister and in blood samples of both parents. Surprisingly, the mutation was neither found in both parents, nor in the tissue samples of the sister. We outline the impact of this finding for genetic counselling and review the literature on FAP and HB.
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http://dx.doi.org/10.1007/s10689-012-9538-2DOI Listing
September 2012

The molecular basis of EPCAM expression loss in Lynch syndrome-associated tumors.

Mod Pathol 2012 Jun 2;25(6):911-6. Epub 2012 Mar 2.

Department of Applied Tumor Biology, Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany.

Germline deletions affecting the epithelial cell adhesion molecule (EPCAM) gene lead to silencing of MSH2 and cause Lynch syndrome. We have recently reported that lack of EPCAM expression occurs in many, but not all tumors from Lynch syndrome patients with EPCAM germline deletions. The differences in EPCAM expression were not related to the localization of EPCAM germline deletions. We therefore hypothesized that the type of the second somatic hit, which leads to MSH2 inactivation during tumor development, determines EPCAM expression in the tumor cells. To test this hypothesis and to evaluate whether lack of EPCAM expression can already be detected in Lynch syndrome-associated adenomas, we analyzed four carcinomas and two adenomas from EPCAM germline deletion carriers for EPCAM protein expression and allelic deletion status of the EPCAM gene region by multiplex ligation-dependent probe amplification. In four out of six tumors we observed lack of EPCAM expression accompanied by biallelic deletions affecting the EPCAM gene. In contrast, monoallelic retention of the EPCAM gene was observed in the remaining two tumors with retained EPCAM protein expression. These results demonstrate that EPCAM expression in tumors from EPCAM deletion carriers depends on the localization of the second somatic hit that inactivates MSH2. Moreover, we report lack of EPCAM protein expression in a colorectal adenoma, suggesting that EPCAM immunohistochemistry may detect EPCAM germline deletions already at a precancerous stage.
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http://dx.doi.org/10.1038/modpathol.2012.30DOI Listing
June 2012

A small terminal deletion 11q in a boy without Jacobsen syndrome: narrowing the critical region for the 11q Jacobsen syndrome phenotype.

Am J Med Genet A 2012 Mar 2;158A(3):680-4. Epub 2012 Feb 2.

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

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http://dx.doi.org/10.1002/ajmg.a.34433DOI Listing
March 2012

Molecular and clinical characterization of an in frame deletion of uncertain clinical significance in the BRCA2 gene.

Breast Cancer Res Treat 2012 Jun 8;133(2):725-34. Epub 2012 Jan 8.

Division Molecular Biology of Breast Cancer, Department of Gynecology and Obstetrics, University of Heidelberg, Heidelberg, Germany.

In this study, we analyzed a "variant of uncertain significance" (VUS) located in exon 23 of the BRCA2 gene exhibited by six members of five distinct families with hereditary breast cancer (BC). The variant was identified by DNA sequencing, and cDNA analysis revealed its co-expression with wild-type mRNA. We analyzed co-occurrence with other pathological mutations in BRCA1/2, performed a case-control study, looked for evolutionary data and used in-silico analyses to predict its potential clinical significance. Sequencing revealed an in frame deletion of 126 nucleotides in exon 23, leading to a deletion of 42 amino acids (c.9203_9328del126, p.Pro2992_Thr3033del). All of the VUS-carriers suffered from either BC or ovarian/pancreatic cancer. No other definite pathologic mutation of BRCA genes was found in the five families. The identified deletion could not be observed in a control cohort of 2,652 healthy individuals, but in 5 out of 916 (0.5%) tested BC families without a bona fide pathogenic BRCA1/2 mutation (P = 0.0011). According to these results, the in frame deletion c.9203_9328del126 is a rare mutation strongly associated with familial BC. In summary, our investigations indicate that this BRCA2 deletion is pathogenic.
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http://dx.doi.org/10.1007/s10549-011-1917-0DOI Listing
June 2012

Incidence of small lymph node metastases with evidence of extracapsular extension: clinical implications in patients with head and neck squamous cell carcinoma.

Int J Radiat Oncol Biol Phys 2010 Dec 16;78(5):1366-72. Epub 2010 Mar 16.

Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Switzerland.

Purpose: Small lymph nodes (LN) show evidence of extracapsular extension (ECE) in a significant number of patients. This study was performed to determine the impact of ECE in LN ≤7 mm as compared with ECE in larger LN.

Methods And Materials: All tumor-positive LN of 74 head and neck squamous cell carcinoma (HNSCC) patients with at least one ECE positive LN were analyzed retrospectively for the LN diameter and the extent of ECE. Clinical endpoints were regional relapse-free survival, distant metastasis-free survival, and overall survival. The median follow-up for the surviving patients was 2.1 years (range, 0.3-9.2 years).

Results: Forty-four of 74 patients (60%) had at least one ECE positive LN ≤10 mm. These small ECE positive LN had a median diameter of 7 mm, which was used as a cutoff. Thirty patients (41%) had at least one ECE positive LN ≤7 mm. In both univariate and multivariate Cox regression analyses, the incidence of at least one ECE positive LN ≤7 mm was a statistically significant prognostic factor for decreased regional relapse-free survival (adjusted hazard ratio [HR]: 2.7, p = 0.03, 95% confidence interval [CI]: 1.1-6.4), distant metastasis-free survival (HR: 2.6, p = 0.04, 95% CI: 1.0-6.6), and overall survival (HR: 2.5, p = 0.03, 95% CI: 1.1-5.8).

Conclusions: The incidence of small ECE positive LN metastases is a significant prognostic factor in HNSCC patients. Small ECE positive LN may represent more invasive tumor biology and could be used as prognostic markers.
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http://dx.doi.org/10.1016/j.ijrobp.2009.09.043DOI Listing
December 2010

Quantitative analysis of extracapsular extension of metastatic lymph nodes and its significance in radiotherapy planning in head and neck squamous cell carcinoma.

Int J Radiat Oncol Biol Phys 2010 Mar 3;76(4):1127-32. Epub 2009 Aug 3.

Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Freiburgstrasse, 3010 Bern, Switzerland.

Purpose: We performed a histopathologic analysis to assess the extent of the extracapsular extension (ECE) beyond the capsule of metastatic lymph nodes (LN) in head and neck cancer to determine appropriate clinical target volume (CTV) expansions.

Methods And Materials: All tumor-positive LN of 98 patients who underwent a neck dissection with evidence of ECE in at least one LN were analyzed by a single pathologist. The largest diameters of all LN, and in the case of ECE, the maximal linear distance, from the capsule to the farthest extent of tumor or tumoral reaction were recorded.

Results: A total of 231 LN with ECE and 200 tumor-positive LN without ECE were analyzed. The incidence of ECE was associated with larger LN size (p < 0.001). Of all tumor-positive LN with a diameter of < 10 mm or < 5 mm, 105/220 (48%) nodes or 17/59 (29%) nodes, respectively, showed evidence of ECE. The mean and median extent values of ECE were 2 and 1 mm (range, 1-10 mm) and the ECE was < or = 5 mm in 97% and < or = 3 mm in 91% of the LN, respectively. Overall, the extent of ECE was significantly correlated with larger LN size (Spearman's correlation coefficient = 0.21; p = 0.001).

Conclusions: The incidence of ECE is associated with larger LN size. However, ECE is found in a substantial number of LN with a diameter of < 10 mm. The use of 10-mm CTV margins around the gross tumor volume seems appropriate to account for ECE in radiotherapy planning of head and neck cancer.
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http://dx.doi.org/10.1016/j.ijrobp.2009.03.065DOI Listing
March 2010

Box 2 region of the oncostatin M receptor determines specificity for recruitment of Janus kinases and STAT5 activation.

J Biol Chem 2008 Jul 22;283(28):19465-77. Epub 2008 Apr 22.

Institut für Biochemie, Universitätsklinikum RWTH Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany.

Human and murine oncostatin M (OSM) induce their bioactivities through a heterodimeric receptor complex consisting of gp130 and the OSM receptor (OSMR), which initiates a signaling pathway involving Janus kinases (JAKs) and transcription factors of the signal transducers and activators of transcription (STAT) family. In contrast to the signal transducing receptor subunit gp130, the OSMR allows strong activation of STAT5B. The underlying molecular mechanism, however, remained unclear. Here we demonstrate that the human and murine OSM receptors use distinct mechanisms for STAT5B activation. The human receptor contains a STAT5B recruiting tyrosine motif (Tyr837/Tyr839) C-terminal to the box 1/2 region, which is absent in the mouse receptor. In contrast, the murine receptor initiates STAT5 activation directly via the receptor bound Janus kinases. Intriguingly, the murine receptor preferentially recruits JAK2, whereas the human receptor seems to have a higher affinity for JAK1. We identify a single amino acid (Phe820) in the human receptor that is responsible for this preference. Exchange by the murine counterpart (Cys815) allows recruitment of JAK2 by the human receptor and consequently activation of STAT5B independently of receptor tyrosine motifs. STAT5B interacts directly with JAK2 only in response to activation of the murine OSMR or the mutated human OSMR. Additionally, we show that OSM-induced STAT1 phosphorylation occurs independently of receptor tyrosine motifs and is mediated directly by Janus kinases, whereas the two C-terminally located tyrosine residues Tyr917/Tyr945 of the OSMR are crucial for STAT3 activation.
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http://dx.doi.org/10.1074/jbc.M710157200DOI Listing
July 2008

Molecular definition of chromosome arm 5q deletion end points and detection of hidden aberrations in patients with myelodysplastic syndromes and isolated del(5q) using oligonucleotide array CGH.

Genes Chromosomes Cancer 2007 Dec;46(12):1119-28

Institute of Human Genetics and Anthropology, Heinrich-Heine-University Duesseldorf, 40225 Duesseldorf, Germany.

Isolated deletions of the long arm of chromosome 5, del(5q), are observed in 10% of myelodysplastic syndromes (MDS) and are associated with a more favorable prognosis, although the clinical course varies considerably. If one or more additional chromosomal aberrations are present, this correlates with a significantly shorter overall survival. To assess the frequency of hidden abnormalities in cases with an isolated cytogenetic del(5q), we have performed a genome wide high resolution 44 K 60mer oligonucleotide array comparative genomic hybridization (aCGH) study using DNA from bone marrow cells of 12 MDS and one AML patient. In one case a single additional hidden 5.6 Mb deletion of 13q14 and in another case multiple larger aberrations involving many chromosomes were found. Fluorescence in situ hybridization demonstrated that aberrations present in 35% of the bone marrow cells can be detected by aCGH. Furthermore with oligonucleotide aCGH the deletion end points in 5q were mapped precisely, revealing a cluster of proximal breakpoints in band q14.3 (n = 8) and a distal cluster between bands q33.2 and q34 (n = 11). This study shows the high resolution of oligonucleotide CGH arrays for precisely mapping genomic alterations and for refinement of deletion end points. In addition, the high sensitivity of this method enables the study of whole bone marrow cells from MDS patients, a disease with a low blast count.
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http://dx.doi.org/10.1002/gcc.20498DOI Listing
December 2007