Publications (45)233.34 Total impact
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Article: The natural course of infantile spinal muscular atrophy with respiratory distress type 1 (SMARD1).
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ABSTRACT: Only scarce information is available on the long-term outcome and the natural course of children with infantile spinal muscular atrophy with respiratory distress type 1 (SMARD1) due to mutations in the IGHMBP2 gene. To describe the natural disease course, to systematically quantify the residual capacities of children with SMARD1 who survive on permanent mechanical respiration, and to identify markers predicting the disease outcome at the time of manifestation. We conducted a longitudinal study of 11 infantile SMARD1 patients over a mean observational period of 7.8 (SD 3.2) years. Disease-specific features were continuously assessed by using a semiquantitative scoring system. Additionally, we analyzed the residual enzymatic activity of 6 IGHMBP2 mutants in our patients. After an initial rapid decline of the clinical score until the age of 2 years, residual capabilities reached a plateau or even improved. The overall clinical outcome was markedly heterogeneous, but clinical scores at the age of 3 months showed a positive linear correlation with the clinical outcome at 1 year and at 4 years of age. If expressed in an in vitro recombinant system, mutations of patients with more favorable outcomes retained residual enzymatic activity. Despite their severe disabilities and symptoms, most SMARD1 patients are well integrated into their home environment and two thirds of them are able to attend kindergarten or school. This information will help to counsel parents at the time of disease manifestation.PEDIATRICS 12/2011; 129(1):e148-56. · 4.47 Impact Factor -
Article: New mutations in the ATM gene and clinical data of 25 AT patients.
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ABSTRACT: Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by cerebellar degeneration, immunodeficiency, oculocutaneous telangiectasias, chromosomal instability, radiosensitivity, and cancer predisposition. The gene mutated in the patients, ATM, encodes a member of the phosphatidylinositol 3-kinase family proteins. The ATM protein has a key role in the cellular response to DNA damage. Truncating and splice site mutations in ATM have been found in most patients with the classical AT phenotype. Here we report of our extensive ATM mutation screening on 25 AT patients from 19 families of different ethnic origin. Previously unknown mutations were identified in six patients including a new homozygous missense mutation, c.8110T>C (p.Cys2704Arg), in a severely affected patient. Comprehensive clinical data are presented for all patients described here along with data on ATM function generated by analysis of cell lines established from a subset of the patients.Neurogenetics 10/2011; 12(4):273-82. · 3.35 Impact Factor -
Article: Identification of a novel candidate gene for non-syndromic autosomal recessive intellectual disability: the WASH complex member SWIP.
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ABSTRACT: High-throughput sequencing has greatly facilitated the elucidation of genetic disorders, but compared with X-linked and autosomal dominant diseases, the search for genetic defects underlying autosomal recessive diseases still lags behind. In a large consanguineous family with autosomal recessive intellectual disability (ARID), we have combined homozygosity mapping, targeted exon enrichment and high-throughput sequencing to identify the underlying gene defect. After appropriate single-nucleotide polymorphism filtering, only two molecular changes remained, including a non-synonymous sequence change in the SWIP [Strumpellin and WASH (Wiskott-Aldrich syndrome protein and scar homolog)-interacting protein] gene, a member of the recently discovered WASH complex, which is involved in actin polymerization and multiple endosomal transport processes. Based on high pathogenicity and evolutionary conservation scores as well as functional considerations, this gene defect was considered as causative for ID in this family. In line with this assumption, we could show that this mutation leads to significantly reduced SWIP levels and to destabilization of the entire WASH complex. Thus, our findings suggest that SWIP is a novel gene for ARID.Human Molecular Genetics 07/2011; 20(13):2585-90. · 7.64 Impact Factor -
Article: Genetic variants within miR-126 and miR-335 are not associated with breast cancer risk.
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ABSTRACT: MicroRNAs (miRNAs) are 20-22 nt non-coding RNAs which promote the degradation of target mRNAs or repression of the translation of mRNAs by sequence specific targeting. Many miRNAs are considered as oncogenes or tumor suppressors. MiR-126 and miR-335 play roles in the suppression of breast cancer metastasis by inhibiting tumor growth, proliferation, and cell invasion. The effects of SNPs within the two miRNAs are still unknown. In our study, we analyzed two SNPs, rs4636297 within miR-126 and rs41272366 within miR-335, in three study populations for a putative association with breast cancer risk. We compared the genotype and allele frequencies of rs4636297 and rs41272366 in 2854 cases versus 3188 controls of the three study populations independently and combined. None of the performed analyses showed statistically significant results. In conclusion, our data suggest that the two genetic variants within miR-126 and miR-335 are not associated with breast cancer risk.Breast Cancer Research and Treatment 11/2010; 127(2):549-54. · 4.43 Impact Factor -
Article: Clinical variability and novel mutations in the NHEJ1 gene in patients with a Nijmegen breakage syndrome-like phenotype.
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ABSTRACT: We have previously shown that mutations in the genes encoding DNA Ligase IV (LIGIV) and RAD50, involved in DNA repair by nonhomologous-end joining (NHEJ) and homologous recombination, respectively, lead to clinical and cellular features similar to those of Nijmegen Breakage Syndrome (NBS). Very recently, a new member of the NHEJ repair pathway, NHEJ1, was discovered, and mutations in patients with features resembling NBS were described. Here we report on five patients from four families of different ethnic origin with the NBS-like phenotype. Sequence analysis of the NHEJ1 gene in a patient of Spanish and in a patient of Turkish origin identified homozygous, previously reported mutations, c.168C>G (p.Arg57Gly) and c.532C>T (p.Arg178Ter), respectively. Two novel, paternally inherited truncating mutations, c.495dupA (p.Asp166ArgfsTer20) and c.526C>T (p.Arg176Ter) and two novel, maternal genomic deletions of 1.9 and 6.9 kb of the NHEJ1 gene, were found in a compound heterozygous state in two siblings of German origin and in one Malaysian patient, respectively. Our findings confirm that patients with NBS-like phenotypes may have mutations in the NHEJ1 gene including multiexon deletions, and show that considerable clinical variability could be observed even within the same family.Human Mutation 09/2010; 31(9):1059-68. · 5.69 Impact Factor -
Article: Fatal cardiac arrhythmia and long-QT syndrome in a new form of congenital generalized lipodystrophy with muscle rippling (CGL4) due to PTRF-CAVIN mutations.
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ABSTRACT: We investigated eight families with a novel subtype of congenital generalized lipodystrophy (CGL4) of whom five members had died from sudden cardiac death during their teenage years. ECG studies revealed features of long-QT syndrome, bradycardia, as well as supraventricular and ventricular tachycardias. Further symptoms comprised myopathy with muscle rippling, skeletal as well as smooth-muscle hypertrophy, leading to impaired gastrointestinal motility and hypertrophic pyloric stenosis in some children. Additionally, we found impaired bone formation with osteopenia, osteoporosis, and atlanto-axial instability. Homozygosity mapping located the gene within 2 Mbp on chromosome 17. Prioritization of 74 candidate genes with GeneDistiller for high expression in muscle and adipocytes suggested PTRF-CAVIN (Polymerase I and transcript release factor/Cavin) as the most probable candidate leading to the detection of homozygous mutations (c.160delG, c.362dupT). PTRF-CAVIN is essential for caveolae biogenesis. These cholesterol-rich plasmalemmal vesicles are involved in signal-transduction and vesicular trafficking and reside primarily on adipocytes, myocytes, and osteoblasts. Absence of PTRF-CAVIN did not influence abundance of its binding partner caveolin-1 and caveolin-3. In patient fibroblasts, however, caveolin-1 failed to localize toward the cell surface and electron microscopy revealed reduction of caveolae to less than 3%. Transfection of full-length PTRF-CAVIN reestablished the presence of caveolae. The loss of caveolae was confirmed by Atomic Force Microscopy (AFM) in combination with fluorescent imaging. PTRF-CAVIN deficiency thus presents the phenotypic spectrum caused by a quintessential lack of functional caveolae.PLoS Genetics 01/2010; 6(3):e1000874. · 8.69 Impact Factor -
Article: A genetic variant in the pre-miR-27a oncogene is associated with a reduced familial breast cancer risk.
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ABSTRACT: MicroRNAs (miRNAs) regulate pathways involved in cell differentiation, proliferation, development, and apoptosis by degradation of target mRNAs and/or repression of their translation. Although the single nucleotide polymorphisms (SNPs) in miRNAs target sites have been studied, the effects of SNPs in miRNAs are largely unknown. In our study, we first systematically sequenced miRNA genes reported to be involved in breast cancer to identify/verify SNPs. We analyzed four SNPs, one located in the pre-miRNA and the other three located in miRNA flanking regions, for a putative association with breast cancer risk. The SNP rs895819, located in the terminal loop of pre-miRNA-27a, showed a protective effect. In a large familial breast cancer study cohort, the rare [G] allele of rs895819 was found to be less frequent in the cases than in the controls, indicating a reduced familial breast cancer risk ([G] vs. [A]: OR = 0.88, 95% CI 0.78-0.99, P = 0.0287). Furthermore, age stratification revealed that the protective effect was mainly observed in the age group < 50 years of age ([G] vs. [A]: OR = 0.83, 95% CI 0.70-0.98, P = 0.0314), whereas no significant effect was observed in the age group >or= 50 years of age, indicating a possible hormone-related effect. It has been shown that artificial mutations in the terminal loop of miR-27a can block the maturation process of the miRNA. We hypothesize that the G-variant of rs895819 might impair the maturation of the oncogenic miR-27a and thus, is associated with familial breast cancer risk.Breast Cancer Research and Treatment 11/2009; 121(3):693-702. · 4.43 Impact Factor -
Article: Human RAD50 deficiency in a Nijmegen breakage syndrome-like disorder.
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ABSTRACT: The MRE11/RAD50/NBN (MRN) complex plays a key role in recognizing and signaling DNA double-strand breaks (DSBs). Hypomorphic mutations in NBN (previously known as NBS1) and MRE11A give rise to the autosomal-recessive diseases Nijmegen breakage syndrome (NBS) and ataxia-telangiectasia-like disorder (ATLD), respectively. To date, no disease due to RAD50 deficiency has been described. Here, we report on a patient previously diagnosed as probably having NBS, with microcephaly, mental retardation, 'bird-like' face, and short stature. At variance with this diagnosis, she never had severe infections, had normal immunoglobulin levels, and did not develop lymphoid malignancy up to age 23 years. We found that she is compound heterozygous for mutations in the RAD50 gene that give rise to low levels of unstable RAD50 protein. Cells from the patient were characterized by chromosomal instability; radiosensitivity; failure to form DNA damage-induced MRN foci; and impaired radiation-induced activation of and downstream signaling through the ATM protein, which is defective in the human genetic disorder ataxia-telangiectasia. These cells were also impaired in G1/S cell-cycle-checkpoint activation and displayed radioresistant DNA synthesis and G2-phase accumulation. The defective cellular phenotype was rescued by wild-type RAD50. In conclusion, we have identified and characterized a patient with a RAD50 deficiency that results in a clinical phenotype that can be classified as an NBS-like disorder (NBSLD).The American Journal of Human Genetics 06/2009; 84(5):605-16. · 10.60 Impact Factor -
Article: Novel mutation in the gamma-S crystallin gene causing autosomal dominant cataract.
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ABSTRACT: To identify the underlying genetic defect in a north Indian family with seven members in three-generations affected with bilateral congenital cataract. Detailed family history and clinical data were recorded. Linkage analysis using fluorescently labeled microsatellite markers for the already known candidate gene loci was performed in combination with mutation screening by bidirectional sequencing. Affected individuals had bilateral congenital cataract. Cataract was of opalescent type with the central nuclear region denser than the periphery. Linkage was excluded for the known cataract candidate gene loci at 1p34-36, 1q21-25 (gap junction protein, alpha 8 [GJA8]), 2q33-36 (crystallin, gamma A [CRYGA], crystallin, gamma B [CRYGB], crystallin, gamma C [CRYGC], crystallin, gamma D [CRYGD], crystallin, beta A2 [CRYBA2]), 3q21-22 (beaded filament structural protein 2, phakinin [BFSP2]), 12q12-14 (aquaporin 0 [AQP0]), 13q11-13 (gap junction protein, alpha 3 [GJA3]), 15q21-22, 16q22-23 (v-maf musculoaponeurotic fibrosarcoma oncogene homolog [MAF], heat shock transcription factor 4 [HSF4]), 17q11-12 (crystallin, beta A1 [CRYBA1]), 17q24, 21q22.3 (crystallin, alpha A [CRYAA]), and 22q11.2 (crystallin, beta B1 [CRYBB1], crystallin, beta B2 [CRYBB2], crystallin, beta B3 [CRYBB3], crystallin, beta A4 [CRYBA4]). Crystallin, alpha B (CRYAB) at chromosome 11q23-24 was excluded by sequence analysis. However, sequencing the candidate gene, crystallin, gamma S (CRYGS), at chromosome 3q26.3-qter showed a heterozygous c.176G-->A change that resulted in the replacement of a structurally highly conserved valine by methionine at codon 42 (p.V42M). This sequence change was not observed in unaffected family members or in the 100 ethnically matched controls. We report a novel missense mutation, p.V42M, in CRYGS associated with bilateral congenital cataract in a family of Indian origin. This is the third report of a mutation in this exceptional member of the beta-/gamma-crystallin superfamily and further substantiates the genetic and clinical heterogeneity of autosomal dominant cataract.Molecular vision 01/2009; 15:476-81. · 2.20 Impact Factor -
Article: Clinical variability in distal spinal muscular atrophy type 1 (DSMA1): determination of steady-state IGHMBP2 protein levels in five patients with infantile and juvenile disease.
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ABSTRACT: Distal spinal muscular atrophy type 1 (DSMA1) is caused by mutations in the immunoglobulin mu-binding protein 2 (IGHMBP2) gene. Patients with DSMA1 present between 6 weeks and 6 months of age with progressive muscle weakness and respiratory failure due to diaphragmatic palsy. Contrary to this "classic" infantile disease, we have previously described a DSMA1 patient with juvenile disease onset. In this paper, we present (1) a second juvenile case and (2) the first study of DSMA1 on protein level in patients with infantile (n = 3) as well as juvenile (n = 2) disease onset observing elevated residual steady-state IGHMBP2 protein levels in the patients with late onset DSMA1 as compared to those with classic DSMA1. Mutation screening in IGHMBP2 revealed two patients compound heterozygous for a novel missense mutation (c.1478C-->T; p.T493I) and another previously described mutation. In lymphoblastoid cells of both patients, steady-state IGHMBP2 protein levels were reduced. In comparison to wild-type IGHMBP2, the p.T493I variant protein had an increased tendency to aggregate and spontaneously degrade in vitro. We verified a change in the physicochemical properties of the p.T493I variant which may explain the pathogenicity of this mutation. Our data further suggest that the age of onset of DSMA1 is variable, and we discuss the effect of residual IGHMBP2 protein levels on the clinical course and the severity of the disease.Journal of Molecular Medicine 10/2008; 87(1):31-41. · 4.67 Impact Factor -
Article: Spinal muscular atrophy with respiratory distress type 1 (SMARD1).
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ABSTRACT: Autosomal recessive spinal muscular atrophy with respiratory distress type 1 (SMARD1), recently referred to as distal spinal muscular atrophy 1 (DSMA1; MIM#604320) and also known as distal hereditary motor neuropathy type 6 (dHMN6 or HMN6), results from mutations in the IGHMBP2 gene on chromosome 11q13.3 encoding the immunoglobulin micro-binding protein 2. In contrast to the infantile spinal muscular atrophy type 1 (SMA1; Werdnig-Hoffmann disease) with weakness predominantly of proximal muscles and bell-shaped thorax deformities due to intercostal muscle atrophy, infants with distal spinal muscular atrophy 1 usually present with distal muscle weakness, foot deformities, and sudden respiratory failure due to diaphragmatic paralysis that often requires urgent intubation. In this article, the authors review the clinical, neuropathological, and genetic aspects of distal spinal muscular atrophy 1 and discuss differential diagnoses.Journal of Child Neurology 03/2008; 23(2):199-204. · 1.75 Impact Factor -
Article: A mutation in GJA8 (p.P88Q) is associated with "balloon-like" cataract with Y-sutural opacities in a family of Indian origin.
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ABSTRACT: To detect the underlying genetic defect in a family with three members in two generations affected with bilateral congenital cataract. Detailed family history and clinical data were recorded. Mutation screening in the candidate genes, alphaA-crystallin (CRYAA), betaA1-crystallin (CRYBA1), betaB2-crystallin (CRYBB2), gammaA-gammaD-crystallins (CRYGA, CRYGB, CRYGC, and CRYGD), connexin-46 (GJA3), and connexin-50 (GJA8), was performed by bidirectional sequencing of the amplified products. Affected individuals had "balloon-like" cataract with prominent Y-sutural opacities. Sequencing of the candidate genes showed a heterozygous c.262C>A change in the gene for connexin 50 (GJA8), which is localized at 1q21, that resulted in the replacement of a highly conserved proline by glutamine (p.P88Q). This sequence change was not observed in 96 ethnically matched controls. We report a p.P88Q mutation in GJA8 associated with Y-sutural cataract in a family of Indian origin. Mutations of the same codon have previously been described in British families with pulverulent cataract, suggesting that modifying factors may determine the type of cataract.Molecular vision 02/2008; 14:1171-5. · 2.20 Impact Factor -
Article: Nijmegen Breakage Syndrome mutations and risk of breast cancer.
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ABSTRACT: Mutations in the NBS1 gene have been identified as disease-causing mutations in patients with Nijmegen Breakage Syndrome (NBS), but their clinical impact on breast cancer susceptibility has remained uncertain. We determined the frequency of 2 NBS mutations, 657del5 and R215W, in two large series of breast cancer cases and controls from Northern Germany and from the Republic of Belarus. The 5-bp-deletion 657del5 was identified in 15/1,588 cases (0.9%) from Belarus and in 1/1,076 cases (0.1%) from Germany but in only 1/1,014 population controls from Belarus and 0/1017 German controls (p < 0.01). The missense substitution R215W was observed in 9/1,588 Byelorussian and 9/1,076 German patients (0.6% and 0.8%, respectively) but was also present in 5/1,014 Byelorussian and 2/1,017 German control individuals (adjusted OR = 1.9, 95%CI 0.8-4.6, p = 0.18). Studies of lymphoblastoid cell lines revealed that NBS1/p95 protein levels were reduced to 70% in cells from a heterozygous breast cancer patient carrying R215W and to 15% in cells from a NBS patient compound heterozygous for 657del5/R215W suggesting that the R215W substitution may be associated with protein instability. Levels of radiation-induced phosphorylation of Nbs1/p95(Ser343) were reduced to 60% and 35% of wildtype, respectively. Neither age at diagnosis nor family history of breast cancer differed significantly between carriers and noncarriers of NBS mutations. The combined data are in line with an about 3-fold increase in breast cancer risk for female NBS heterozygotes (OR 3.1; 95%CI 1.4-6.6) and indicate that the 657del5 deletion and perhaps the R215W substitution contribute to inherited breast cancer susceptibility in Central and Eastern Europe.International Journal of Cancer 02/2008; 122(4):802-6. · 5.44 Impact Factor -
Article: A novel mutation in GJA8 associated with jellyfish-like cataract in a family of Indian origin.
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ABSTRACT: To identify the underlying genetic defect in a three-generation family with five members affected with dominant bilateral congenital cataract and microcornea. Detailed family history and clinical data were recorded. Mutation screening in the candidate genes, CRYAA, CRYBB1, MAF, GJA3, and GJA8, was performed by bidirectional sequencing of the amplified products. Affected individuals had a jellyfish-like cataract in association with microcornea. Sequencing of GJA8 (connexin 50) showed a novel, heterozygous c.134G-->C change that resulted in the substitution of a highly conserved tryptophan by serine (p.W45S). This sequence change segregated completely with the disease phenotype and was not observed in 108 ethnically matched controls (216 chromosomes). However, an identical substitution has previously been described in GJA3 (connexin 46) leading to autosomal dominant nuclear cataract without microcornea. This is a novel mutation identified in the first transmembrane domain (M1) of GJA8. These findings further expand the mutation spectrum of connexin 50 (Cx50) in association with congenital cataract and microcornea.Molecular vision 01/2008; 14:323-6. · 2.20 Impact Factor -
Article: Cancer risk of heterozygotes with the NBN founder mutation.
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ABSTRACT: The autosomal recessive chromosomal instability disorder Nijmegen breakage syndrome (NBS) is associated with increased risk of lymphoid malignancies and other cancers. Cells from NBS patients contain many double-stranded DNA breaks. More than 90% of NBS patients are homozygous for a founder mutation, 657del5, in the NBN gene. We investigated the 657del5 carrier status of cancer patients among blood relatives (i.e., first-, through fourth-degree relatives) of NBS patients in the Czech Republic and Slovakia to test the hypothesis that NBN heterozygotes have an increased cancer risk. Medical information was compiled from 344 blood relatives of NBS patients in 24 different NBS families from January 1, 1998, through December 31, 2003. The 657del5 carrier status of subjects was unknown at the time of their recruitment but was later determined from blood samples collected at the time of the interview. Medical records and death certificates were used to confirm a diagnosis of cancer. For the relatives with cancer who are not obligate heterozygotes (such as parents and two grandparents in consanguineous families), the observed and expected number of mutation carriers were compared by use of the index-test method, which estimated the risk of cancer associated with carrying the mutation. All P values were two-sided. Thirteen of the 344 blood relatives had confirmed cases of any type of cancer; 11 of these 13 cancer patients carried the NBN 657del5 mutation, compared with 6.0 expected (P = .005). Among the 56 grandparents with complete data from 14 NBS families, 10 of the 28 carriers of 657del5, but only one of the 28 noncarriers, developed cancer (odds ratio = 10.7, 95% CI = 1.4 to 81.5; P<.004). The NBN 657del5 mutation appears to be associated with an elevated risk of cancer in heterozygotes.CancerSpectrum Knowledge Environment 01/2008; 99(24):1875-80. · 14.07 Impact Factor -
Article: Clinical and mutational profile in spinal muscular atrophy with respiratory distress (SMARD): defining novel phenotypes through hierarchical cluster analysis.
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ABSTRACT: Autosomal recessive spinal muscular atrophy with respiratory distress (SMARD) is a heterogeneous disorder. Mutations in the immunoglobulin micro-binding protein gene (IGHMBP2) lead to SMARD1, but clinical criteria that delineate SMARD1 from other SMARD syndromes are not well established. Here we present a retrospective clinical and genetic study to determine the criteria that would predict the presence or absence of IGHMBP2 mutations. From 141 patients with respiratory distress and a spinal muscular atrophy phenotype we recorded the clinical features through a questionnaire and sequenced the entire coding region of IGHMBP2. In 47 (33%) patients we identified IGHMBP2 mutations, 14 of which were not described before. Clinical features and combinations thereof associated with the presence of IGHMBP2 mutations were discovered through hierarchical cluster analysis. This method detects common traits not evident at first sight by grouping items according to their similarity. The combination of "manifestation of respiratory failure between 6 weeks and 6 months" AND ("presence of diaphragmatic eventration" OR "preterm birth") predicted the presence of IGHMBP2 mutations with 98% sensitivity and 92% specificity. Non-SMARD1 patients fell into two different symptom clusters, mainly separated by the age at respiratory failure and the presence of multiple congenital contractures. The 14 novel IGHMBP2 mutations comprised missense, frameshift, splice-site, and nonsense mutations. All missense mutations altered conserved residues within or adjacent to the putative DNA helicase domain. The c.1235+3A>G splice-site mutation did not entirely suppress correct splicing and we found a residual wild-type IGHMBP2 mRNA steady-state level of 24.4+/-6.9%, which was, however, not sufficient to avert SMARD1 in this patient.Human Mutation 08/2007; 28(8):808-15. · 5.69 Impact Factor -
Article: Molecular genetic analysis of NBS1 in German melanoma patients.
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ABSTRACT: The aim of this study was to investigate the role of NBS1 in the pathogenesis of malignant melanoma of the skin. To exclude the common 657del5 founder mutation, a total of 376 melanoma patients from Southern Germany were analyzed for sequence alterations in exon 6 of NBS1 by direct sequencing. Analyses revealed one 657del5 mutation and three nonsynonymous sequence variations in exon 6 of NBS1 (V210F, R215W, and F222L). Analysis of an additional sample of 629 melanoma patients and 604 controls revealed no F222L mutation, indicating that this newly identified sequence alteration is not a common polymorphism. In a case-control association study including 632 melanoma patients and 615 cancer-free control participants from Southern Germany, three publicly known single nucleotide polymorphisms located in the NBS1 gene region were analyzed. No significant associations between single nucleotide polymorphisms (rs9995, rs867185 and rs1063045) or referring calculated haplotypes and melanoma risk were identified. These results suggest that NBS1 does not play a major role in predisposition to melanoma in the Southern German population but that alterations of this gene might contribute to the risk of this cancer.Melanoma Research 05/2007; 17(2):109-16. · 2.19 Impact Factor -
Article: Cancer incidence in Nijmegen breakage syndrome is modulated by the amount of a variant NBS protein.
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ABSTRACT: The human genetic disorder, Nijmegen breakage syndrome (NBS), is characterized by radiosensitivity, immunodeficiency and an increased risk for cancer, particularly B-cell non-Hodgkin lymphoma. The NBS1 gene codes for a protein, nibrin, involved in the processing/repair of DNA double-strand breaks and in cell cycle checkpoints. The majority of patients are homozygous for a founder mutation, a 5 bp deletion. This mutation is actually hypomorphic, since a functionally relevant truncated protein, of approximately 70 kDa, is produced by alternative translation. Null mutation of the homologous gene in mice is lethal; however, null-mutant murine cells can be rescued by a human NBS1 cDNA carrying the founder mutation. Clearly, the truncated p70-nibrin is able to sustain vital cellular functions of the full-length protein. We have used semi-quantitative immunoprecipitation to examine a panel of 26 lymphoblastoid B-cell lines from NBS patients for their level of p70-nibrin expression and correlate this with details of clinical phenotype provided by the two contributing centres. We find considerable variation in the amount of p70-nibrin in cell lines from different patients. Examination of clinical history indicated a clear and statistically significant correlation between p70-nibrin expression levels and lymphoma incidence. The variation in p70-nibrin levels between patients probably reflects the susceptibility of the alternative translation process to other genetic and non-genetic factors. Patients whose cells are able to maintain particularly high levels of the truncated p70-nibrin protein are at a lower risk for lymphoma than those patients with low levels of p70-nibrin in their cells.Carcinogenesis 02/2007; 28(1):107-11. · 5.70 Impact Factor -
Article: Successful bone marrow transplantation in a patient with DNA ligase IV deficiency and bone marrow failure.
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ABSTRACT: DNA Ligase IV deficiency syndrome is a rare autosomal recessive disorder caused by hypomorphic mutations in the DNA ligase IV gene (LIG4). The clinical phenotype shows overlap with a number of other rare syndromes, including Seckel syndrome, Nijmegen breakage syndrome, and Fanconi anemia. Thus the clinical diagnosis is often delayed and established by exclusion. We describe a patient with pre- and postnatal growth retardation and dysmorphic facial features in whom the diagnoses of Seckel-, Dubowitz-, and Nijmegen breakage syndrome were variably considered. Cellular radiosensitivity in the absence of clinical manifestations of Ataxia telangiectasia lead to the diagnosis of DNA ligase IV (LIG4) deficiency syndrome, confirmed by compound heterozygous mutations in the LIG4 gene. At age 11, after a six year history of progressive bone marrow failure and increasing transfusion dependency the patient was treated with matched sibling donor hematopoietic stem cell transplantation (HSCT) using a fludarabine-based conditioning regimen without irradiation. The post-transplantation course was uneventful with rapid engraftment leading to complete and stable chimerism. Now at age 16, the patient has gained weight and is in good clinical condition. HSCT using mild conditioning without irradiation qualifies as treatment of choice in LIG4-deficient patients who have a matched sibling donor.Orphanet Journal of Rare Diseases 02/2007; 2:5. · 5.83 Impact Factor -
Article: Nijmegen breakage syndrome (NBS) due to maternal isodisomy of chromosome 8.
American Journal of Medical Genetics Part A 02/2007; 143(1):92-4. · 2.39 Impact Factor
Top co-authors
Top Journals
Institutions
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2010
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The Royal Hospital
Muscat, Muhafazat Masqat, Oman
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2004–2010
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Charité Universitätsmedizin Berlin
- • Institute of Medical Genetics and Human Genetics
- • Department of Pediatrics, Division of Neurology
Berlin, Land Berlin, Germany
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2002–2010
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Humboldt-Universität zu Berlin
- Institute of Medical Genetics and Human Genetics
Berlin, Land Berlin, Germany
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2007–2009
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Guru Nanak Dev University
- Department of Human Genetics
Amritsar, State of Punjab, India -
Freie Universität Berlin
- Department of Biology, Chemistry, and Pharmacy
Berlin, Land Berlin, Germany
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2008
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Charles University in Prague
Praha, Hlavni mesto Praha, Czech Republic
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2004–2007
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Maria Sklodowska Curie Memorial Cancer Centre
Gliwice, Silesian Voivodeship, Poland
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2003
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Università Degli Studi Roma Tre
Roma, Latium, Italy
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