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Pacot L, Girish M, Knight S, Spurlock G, Varghese V, Ye M, Thomas N, Pasmant E, Upadhyaya M. Correlation between large rearrangements and patient phenotypes in NF1 deletion syndrome: an update and review. BMC Med Genomics 2024; 17:73. [PMID: 38448973 PMCID: PMC10919053 DOI: 10.1186/s12920-024-01843-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 03/01/2024] [Indexed: 03/08/2024] Open
Abstract
About 5-10% of neurofibromatosis type 1 (NF1) patients exhibit large genomic germline deletions that remove the NF1 gene and its flanking regions. The most frequent NF1 large deletion is 1.4 Mb, resulting from homologous recombination between two low copy repeats. This "type-1" deletion is associated with a severe clinical phenotype in NF1 patients, with several phenotypic manifestations including learning disability, a much earlier development of cutaneous neurofibromas, an increased tumour risk, and cardiovascular malformations. NF1 adjacent co-deleted genes could act as modifier loci for the specific clinical manifestations observed in deleted NF1 patients. Furthermore, other genetic modifiers (such as CNVs) not located at the NF1 locus could also modulate the phenotype observed in patients with large deletions. In this study, we analysed 22 NF1 deletion patients by genome-wide array-CGH with the aim (1) to correlate deletion length to observed phenotypic features and their severity in NF1 deletion syndrome, and (2) to identify whether the deletion phenotype could also be modulated by copy number variations elsewhere in the genome. We then review the role of co-deleted genes in the 1.4 Mb interval of type-1 deletions, and their possible implication in the main clinical features observed in this high-risk group of NF1 patients.
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Affiliation(s)
- Laurence Pacot
- Fédération de Génétique et Médecine Génomique, Hôpital Cochin, DMU BioPhyGen, AP-HP, Centre-Université Paris Cité, Paris, France
- Institut Cochin, Inserm U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France
| | - Milind Girish
- School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Samantha Knight
- School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | | | - Vinod Varghese
- All Wales Medical Genomics Service, Cardiff, Great Britain
| | - Manuela Ye
- Institut Cochin, Inserm U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France
| | - Nick Thomas
- School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Eric Pasmant
- Fédération de Génétique et Médecine Génomique, Hôpital Cochin, DMU BioPhyGen, AP-HP, Centre-Université Paris Cité, Paris, France.
- Institut Cochin, Inserm U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France.
| | - Meena Upadhyaya
- Division of Cancer and Genetics, Institute of Medical Genetics, Cardiff University, Heath Park, CF14 4XN, Cardiff, UK
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2
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Pacot L, Ye M, Nectoux J, Laurendeau I, Briand-Suleau A, Coustier A, Maillard T, Barbance C, Orhant L, Vaucouleur N, Blanché H, Parfait B, Wolkenstein P, Vidaud M, Vidaud D, Pasmant E. Droplet Digital PCR for Fast and Accurate Characterization of NF1 Locus Deletions: Confirmation of the Predominant Maternal Origin of Type-1 Deletions. J Mol Diagn 2024; 26:150-157. [PMID: 38008284 DOI: 10.1016/j.jmoldx.2023.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/09/2023] [Accepted: 11/07/2023] [Indexed: 11/28/2023] Open
Abstract
Neurofibromatosis type-1 is a genetic disorder caused by loss-of-function variants in the tumor-suppressor NF1. Approximately 4% to 11% of neurofibromatosis type-1 patients have a NF1 locus complete deletion resulting from nonallelic homologous recombination between low copy repeats. Codeleted genes probably account for the more severe phenotype observed in NF1-deleted patients. This genotype-phenotype correlation highlights the need for a detailed molecular description. A droplet digital PCR (ddPCR) set along the NF1 locus was designed to delimitate the three recurrent NF1 deletion breakpoints. The ddPCR was tested in 121 samples from nonrelated NF1-deleted patients. Classification based on ddPCR versus multiplex ligation-dependent probe amplification (MLPA) was compared. In addition, microsatellites were analyzed to identify parental origin of deletions. ddPCR identified 77 type-1 (64%), 20 type-2 (16%), 7 type-3 (6%), and 17 atypical deletions (14%). The results were comparable with MLPA, except for three atypical deletions misclassified as type-2 using MLPA, for which the SUZ12 gene was not deleted. A significant maternal bias (25 of 30) in the origin of deletions was identified. This study proposes a fast and efficient ddPCR quantification to allow fine NF1 deletion classification. It indicates that ddPCR can be implemented easily into routine diagnosis to complement the techniques dedicated to NF1 point variant identification. This new tool may help unravel the genetic basis conditioning phenotypic variability in NF1-deleted patients and offer tailored genetic counseling.
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Affiliation(s)
- Laurence Pacot
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France; Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - Manuela Ye
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France
| | - Juliette Nectoux
- Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - Ingrid Laurendeau
- Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - Audrey Briand-Suleau
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France; Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - Audrey Coustier
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France
| | - Théodora Maillard
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France
| | - Cécile Barbance
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France
| | - Lucie Orhant
- Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - Nicolas Vaucouleur
- Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | | | - Béatrice Parfait
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France; Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - Pierre Wolkenstein
- Department of Dermatology, Hôpital Henri Mondor, Assistance Publique-Hôpital Paris, Créteil, France; INSERM, Clinical Investigation Center 1430, Referral Center of Neurofibromatosis, Hôpital Henri Mondor, Assistance Publique-Hôpital Paris, Faculté de Santé Paris Est Créteil, Créteil, France
| | - Michel Vidaud
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France; Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - Dominique Vidaud
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France; Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France
| | - Eric Pasmant
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Cité, CARPEM, Paris, France; Fédération de Génétique et Médecine Génomique, DMU BioPhyGen, Assistance Publique-Hôpital Paris, Centre-Université Paris Cité, Hôpital Cochin, Paris, France.
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3
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Kehrer-Sawatzki H, Wahlländer U, Cooper DN, Mautner VF. Atypical NF1 Microdeletions: Challenges and Opportunities for Genotype/Phenotype Correlations in Patients with Large NF1 Deletions. Genes (Basel) 2021; 12:genes12101639. [PMID: 34681033 PMCID: PMC8535936 DOI: 10.3390/genes12101639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 09/30/2021] [Accepted: 10/14/2021] [Indexed: 11/16/2022] Open
Abstract
Patients with neurofibromatosis type 1 (NF1) and type 1 NF1 deletions often exhibit more severe clinical manifestations than patients with intragenic NF1 gene mutations, including facial dysmorphic features, overgrowth, severe global developmental delay, severe autistic symptoms and considerably reduced cognitive abilities, all of which are detectable from a very young age. Type 1 NF1 deletions encompass 1.4 Mb and are associated with the loss of 14 protein-coding genes, including NF1 and SUZ12. Atypical NF1 deletions, which do not encompass all 14 protein-coding genes located within the type 1 NF1 deletion region, have the potential to contribute to the delineation of the genotype/phenotype relationship in patients with NF1 microdeletions. Here, we review all atypical NF1 deletions reported to date as well as the clinical phenotype observed in the patients concerned. We compare these findings with those of a newly identified atypical NF1 deletion of 698 kb which, in addition to the NF1 gene, includes five genes located centromeric to NF1. The atypical NF1 deletion in this patient does not include the SUZ12 gene but does encompass CRLF3. Comparative analysis of such atypical NF1 deletions suggests that SUZ12 hemizygosity is likely to contribute significantly to the reduced cognitive abilities, severe global developmental delay and facial dysmorphisms observed in patients with type 1 NF1 deletions.
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Affiliation(s)
- Hildegard Kehrer-Sawatzki
- Institute of Human Genetics, University of Ulm, 89081 Ulm, Germany
- Correspondence: ; Tel.: +49-731-500-65421
| | - Ute Wahlländer
- Kliniken des Bezirks Oberbayern (KBO), Children Clinical Center Munich, 81377 Munich, Germany;
| | - David N. Cooper
- Institute of Medical Genetics, Cardiff University, Heath Park, Cardiff CF14 4XN, UK;
| | - Victor-Felix Mautner
- Department of Neurology, University Hospital Hamburg Eppendorf, 20246 Hamburg, Germany;
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4
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Imagawa E, Higashimoto K, Sakai Y, Numakura C, Okamoto N, Matsunaga S, Ryo A, Sato Y, Sanefuji M, Ihara K, Takada Y, Nishimura G, Saitsu H, Mizuguchi T, Miyatake S, Nakashima M, Miyake N, Soejima H, Matsumoto N. Mutations in genes encoding polycomb repressive complex 2 subunits cause Weaver syndrome. Hum Mutat 2017; 38:637-648. [PMID: 28229514 DOI: 10.1002/humu.23200] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 02/13/2017] [Accepted: 02/18/2017] [Indexed: 12/30/2022]
Abstract
Weaver syndrome (WS) is a rare congenital overgrowth disorder caused by heterozygous mutations in EZH2 (enhancer of zeste homolog 2) or EED (embryonic ectoderm development). EZH2 and EED are core components of the polycomb repressive complex 2 (PRC2), which possesses histone methyltransferase activity and catalyzes trimethylation of histone H3 at lysine 27. Here, we analyzed eight probands with clinically suspected WS by whole-exome sequencing and identified three mutations: a 25.4-kb deletion partially involving EZH2 and CUL1 (individual 1), a missense mutation (c.707G>C, p.Arg236Thr) in EED (individual 2), and a missense mutation (c.1829A>T, p.Glu610Val) in SUZ12 (suppressor of zeste 12 homolog) (individual 3) inherited from her father (individual 4) with a mosaic mutation. SUZ12 is another component of PRC2 and germline mutations in SUZ12 have not been previously reported in humans. In vitro functional analyses demonstrated that the identified EED and SUZ12 missense mutations cause decreased trimethylation of lysine 27 of histone H3. These data indicate that loss-of-function mutations of PRC2 components are an important cause of WS.
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Affiliation(s)
- Eri Imagawa
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Ken Higashimoto
- Division of Molecular Genetics and Epigenetics, Department of Biomolecular Sciences, Faculty of Medicine, Saga University, Saga, Japan
| | - Yasunari Sakai
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Chikahiko Numakura
- Department of Pediatrics, Yamagata University School of Medicine, Yamagata, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Satoko Matsunaga
- Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Akihide Ryo
- Department of Microbiology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Yoshinori Sato
- Department of Molecular Biology, Yokohama City University School of Medicine, Yokohama, Japan
| | - Masafumi Sanefuji
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kenji Ihara
- Department of Pediatrics, Faculty of Medicine, Oita University, Yufu, Japan
| | - Yui Takada
- Department of Pediatrics, Japanese Red Cross Fukuoka Hospital, Fukuoka, Japan
| | - Gen Nishimura
- Department of Pediatric Imaging, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Takeshi Mizuguchi
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Satoko Miyatake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Mitsuko Nakashima
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Hidenobu Soejima
- Division of Molecular Genetics and Epigenetics, Department of Biomolecular Sciences, Faculty of Medicine, Saga University, Saga, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
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5
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Emerging genotype-phenotype relationships in patients with large NF1 deletions. Hum Genet 2017; 136:349-376. [PMID: 28213670 PMCID: PMC5370280 DOI: 10.1007/s00439-017-1766-y] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 02/08/2017] [Indexed: 02/07/2023]
Abstract
The most frequent recurring mutations in neurofibromatosis type 1
(NF1) are large deletions encompassing the NF1
gene and its flanking regions (NF1
microdeletions). The majority of these deletions encompass 1.4-Mb and are associated
with the loss of 14 protein-coding genes and four microRNA genes. Patients with
germline type-1 NF1 microdeletions frequently
exhibit dysmorphic facial features, overgrowth/tall-for-age stature, significant
delay in cognitive development, large hands and feet, hyperflexibility of joints and
muscular hypotonia. Such patients also display significantly more cardiovascular
anomalies as compared with patients without large deletions and often exhibit
increased numbers of subcutaneous, plexiform and spinal neurofibromas as compared
with the general NF1 population. Further, an extremely high burden of internal
neurofibromas, characterised by >3000 ml tumour volume, is encountered
significantly, more frequently, in non-mosaic NF1
microdeletion patients than in NF1 patients lacking such deletions. NF1 microdeletion patients also have an increased risk of
malignant peripheral nerve sheath tumours (MPNSTs); their lifetime MPNST risk is
16–26%, rather higher than that of NF1 patients with intragenic NF1 mutations (8–13%). NF1 microdeletion patients, therefore, represent a high-risk group for
the development of MPNSTs, tumours which are very aggressive and difficult to treat.
Co-deletion of the SUZ12 gene in addition to
NF1 further increases the MPNST risk in
NF1 microdeletion patients. Here, we summarise
current knowledge about genotype–phenotype relationships in NF1 microdeletion patients and discuss the potential role of the genes
located within the NF1 microdeletion interval
whose haploinsufficiency may contribute to the more severe clinical
phenotype.
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6
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Tenorio J, Mansilla A, Valencia M, Martínez-Glez V, Romanelli V, Arias P, Castrejón N, Poletta F, Guillén-Navarro E, Gordo G, Mansilla E, García-Santiago F, González-Casado I, Vallespín E, Palomares M, Mori MA, Santos-Simarro F, García-Miñaur S, Fernández L, Mena R, Benito-Sanz S, del Pozo Á, Silla JC, Ibañez K, López-Granados E, Martín-Trujillo A, Montaner D, Heath KE, Campos-Barros Á, Dopazo J, Nevado J, Monk D, Ruiz-Pérez VL, Lapunzina P. A new overgrowth syndrome is due to mutations in RNF125. Hum Mutat 2015; 35:1436-41. [PMID: 25196541 DOI: 10.1002/humu.22689] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 08/26/2014] [Indexed: 11/08/2022]
Abstract
Overgrowth syndromes (OGS) are a group of disorders in which all parameters of growth and physical development are above the mean for age and sex. We evaluated a series of 270 families from the Spanish Overgrowth Syndrome Registry with no known OGS. We identified one de novo deletion and three missense mutations in RNF125 in six patients from four families with overgrowth, macrocephaly, intellectual disability, mild hydrocephaly, hypoglycemia, and inflammatory diseases resembling Sjögren syndrome. RNF125 encodes an E3 ubiquitin ligase and is a novel gene of OGS. Our studies of the RNF125 pathway point to upregulation of RIG-I-IPS1-MDA5 and/or disruption of the PI3K-AKT and interferon signaling pathways as the putative final effectors.
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Affiliation(s)
- Jair Tenorio
- CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain; Molecular Endocrinology Unit - Overgrowth Syndromes Laboratory, INGEMM, Instituto de Genética Médica y Molecular, IdiPAZ, Hospital Universitario La Paz, Universidad Autónoma de Madrid (UAM), Madrid, Spain
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7
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Visser R, Koelma N, Vijfhuizen L, van der Wielen MJR, Kant SG, Breuning MH, Wit JM, Losekoot M. RNF135 mutations are not present in patients with Sotos syndrome-like features. Am J Med Genet A 2009; 149A:806-8. [PMID: 19291764 DOI: 10.1002/ajmg.a.32694] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Remco Visser
- Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
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8
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Douglas J, Cilliers D, Coleman K, Tatton-Brown K, Barker K, Bernhard B, Burn J, Huson S, Josifova D, Lacombe D, Malik M, Mansour S, Reid E, Cormier-Daire V, Cole T, Rahman N. Mutations in RNF135, a gene within the NF1 microdeletion region, cause phenotypic abnormalities including overgrowth. Nat Genet 2007; 39:963-5. [PMID: 17632510 DOI: 10.1038/ng2083] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Accepted: 05/22/2007] [Indexed: 11/08/2022]
Abstract
17q11 microdeletions that encompass NF1 cause 5%-10% of cases of neurofibromatosis type 1, and individuals with microdeletions are typically taller than individuals with intragenic NF1 mutations, suggesting that deletion of a neighboring gene might promote human growth. We identified mutations in RNF135, which is within the NF1 microdeletion region, in six families characterized by overgrowth, learning disability, dysmorphic features and variable additional features. These data identify RNF135 as causative of a new overgrowth syndrome and demonstrate that RNF135 haploinsufficiency contributes to the phenotype of NF1 microdeletion cases.
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Affiliation(s)
- Jenny Douglas
- Section of Cancer Genetics, Institute of Cancer Research, Sutton, Surrey SM2 5NG, UK
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9
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Mensink KA, Ketterling RP, Flynn HC, Knudson RA, Lindor NM, Heese BA, Spinner RJ, Babovic-Vuksanovic D. Connective tissue dysplasia in five new patients with NF1 microdeletions: further expansion of phenotype and review of the literature. J Med Genet 2006; 43:e8. [PMID: 16467218 PMCID: PMC2603036 DOI: 10.1136/jmg.2005.034256] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Approximately 5% of patients with neurofibromatosis type 1 (NF1) have deletions of the entire NF1 gene. The phenotype usually includes early onset, large number of neurofibromas, presence of congenital anomalies, cognitive deficiency, and variable dysmorphic features and growth abnormalities. Connective tissue abnormalities are not generally recognised as a part of NF1 microdeletion syndrome, but mitral valve prolapse, joint laxity, and/or soft skin on the palms have been reported in a few patients. We describe clinical findings in six newly diagnosed patients with NF1 microdeletions, five of whom presented with connective tissue abnormalities. A literature review of the clinical findings associated with NF1 microdeletion was also performed. Our report confirms that connective tissue dysplasia is common in patients with NF1 microdeletions. Given the potential for associated cardiac manifestation, screening by echocardiogram may be warranted. Despite the large number (>150) of patients with known NF1 microdeletions, the clinical phenotype remains incompletely defined. Additional reports of patients with NF1 microdeletions, including comprehensive clinical and molecular information, are needed to elucidate possible genotype-phenotype correlation.
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10
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De Raedt T, Maertens O, Chmara M, Brems H, Heyns I, Sciot R, Majounie E, Upadhyaya M, De Schepper S, Speleman F, Messiaen L, Vermeesch JR, Legius E. Somatic loss of wild typeNF1 allele in neurofibromas: Comparison ofNF1 microdeletion and non-microdeletion patients. Genes Chromosomes Cancer 2006; 45:893-904. [PMID: 16830335 DOI: 10.1002/gcc.20353] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Neurofibromatosis type I (NF1) is an autosomal dominant familial tumor syndrome characterized by the presence of multiple benign neurofibromas. In 95% of NF1 individuals, a mutation is found in the NF1 gene, and in 5% of the patients, the germline mutation consists of a microdeletion that includes the NF1 gene and several flanking genes. We studied the frequency of loss of heterozygosity (LOH) in the NF1 region as a mechanism of somatic NF1 inactivation in neurofibromas from NF1 patients with and without a microdeletion. There was a statistically significant difference between these two patient groups in the proportion of neurofibromas with LOH. None of the 40 neurofibromas from six different NF1 microdeletion patients showed LOH, whereas LOH was observed in 6/28 neurofibromas from five patients with an intragenic NF1 mutation (P = 0.0034, Fisher's exact). LOH of the NF1 microdeletion region in NF1 microdeletion patients would de facto lead to a nullizygous state of the genes located in the deletion region and might be lethal. The mechanisms leading to LOH were further analyzed in six neurofibromas. In two out of six neurofibromas, a chromosomal microdeletion was found; in three, a mitotic recombination was responsible for the observed LOH; and in one, a chromosome loss with reduplication was present. These data show an important difference in the mechanisms of second hit formation in the 2 NF1 patient groups. We conclude that NF1 is a familial tumor syndrome in which the type of germline mutation influences the type of second hit in the tumors.
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Affiliation(s)
- Thomas De Raedt
- Center for Human Genetics, University Hospital Leuven, Catholic University of Leuven, Leuven, Belgium
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11
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Abstract
Weaver syndrome is a rare disorder of unknown etiology characterized by skeletal overgrowth, distinctive craniofacial and digital abnormalities, and advanced bone age. The prime anesthetic problem reported in children with Weaver syndrome is difficulty with tracheal intubation, resulting in part from relative micrognathia, short neck, and an anterior and cephalad position of the larynx. In this report, the authors describe their experience with two children diagnosed with Weaver syndrome who presented for dental surgery. Contrary to previous reports, tracheal intubation was accomplished with relative ease, suggesting that difficulty in intubation in Weaver syndrome may be age-related, diminishing with advancing age and growth of the mandible, as has been reported for other micrognathic syndromes such as Pierre Robin sequence.
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Affiliation(s)
- Mark W Crawford
- Department of Anesthesia, The Hospital for Sick Children, University of Toronto, Ontario, Canada.
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12
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Merks JHM, Caron HN, Hennekam RCM. High incidence of malformation syndromes in a series of 1,073 children with cancer. Am J Med Genet A 2005; 134A:132-43. [PMID: 15712196 DOI: 10.1002/ajmg.a.30603] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Constitutional molecular defects are known to play a role in oncogenesis, as shown by the increased incidence of embryonic cancers in children with Beckwith-Wiedemann syndrome (BWS) or of leukemia in children with Down syndrome. To establish the incidence and spectrum of malformation syndromes associated with childhood cancer we performed a clinical morphological examination on a series of 1,073 children with cancer. We diagnosed a syndrome in 42 patients (3.9%) and suspected the presence of a syndrome in another 35 patients (3.3%), for a total of 7.2%. This incidence of patients with a proven or suspected syndrome is high, and points to a possible association. We describe new syndrome-tumor associations in several entities: cleidocranial dysostosis (Wilms tumor), Bardet-Biedl syndrome (BBS) (acute lymphoblastic leukemia), Kabuki syndrome (neuroblastoma), LEOPARD syndrome (neuroblastoma), Poland anomaly (osteosarcoma; Hodgkin disease), and blepharophimosis epicanthus inversus syndrome (Burkitt lymphoma). Twenty of the 42 syndrome diagnoses were not recognized in the patients prior to this study, indicating that these diagnoses are commonly missed. We propose that all children with a malignancy should be examined by a clinical geneticist or a pediatrician skilled in clinical morphology to determine if the patients have a malformation syndrome.
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Affiliation(s)
- Johannes Hans M Merks
- Department of Pediatric Oncology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands.
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13
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Spiegel M, Oexle K, Horn D, Windt E, Buske A, Albrecht B, Prott EC, Seemanová E, Seidel J, Rosenbaum T, Jenne D, Kehrer-Sawatzki H, Tinschert S. Childhood overgrowth in patients with common NF1 microdeletions. Eur J Hum Genet 2005; 13:883-8. [PMID: 15856072 DOI: 10.1038/sj.ejhg.5201419] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
While growth retardation and short stature are well-known features of patients with classical neurofibromatosis type 1 (NF1), we found advanced height growth and accelerated carpal bone age in patients with an NF1 microdeletion. Our analysis is based on growth data of 21 patients with common 1.4/1.2 Mb microdeletions, including three patients with a Weaver-like appearance. Overgrowth was most evident in preschool children (2-6 years, n=10, P=0.02). We conclude that childhood overgrowth is part of the phenotypic spectrum in patients with the common 1.4/1.2 Mb NF1 microdeletions and assume that the chromosomal region comprised by the microdeletions contains a gene whose haploinsufficiency causes overgrowth.
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Affiliation(s)
- Miriam Spiegel
- Institut für Medizinische Genetik, Charité, Humboldt-Universität, Berlin, Germany
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14
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Kehrer-Sawatzki H, Kluwe L, Fünsterer C, Mautner VF. Extensively high load of internal tumors determined by whole body MRI scanning in a patient with neurofibromatosis type 1 and a non-LCR-mediated 2-Mb deletion in 17q11.2. Hum Genet 2005; 116:466-75. [PMID: 15776250 DOI: 10.1007/s00439-005-1265-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Accepted: 01/05/2005] [Indexed: 10/25/2022]
Abstract
Deletions in 17q11.2 affecting the NF1 gene and surrounding regions occur in 5% of patients with NF1. The two major types of NF1 deletions encompass 1.4-Mb and 1.2-Mb, respectively, and have breakpoints in the NF1 low-copy repeats or in the JJAZ gene and its pseudogene. Deletions larger than 1.4-Mb are rare, and only seven cases have been reported so far. Here, we describe a 26-year-old NF1 patient with an "atypical" NF1 deletion of 2-Mb. In contrast to the 1.4-Mb deletions, which preferentially occur by interchromosomal recombination during maternal meiosis, the deletion described here occurred intrachromosomally on the paternal chromosome. The centromeric deletion breakpoint lies in an L1-element located 1.3-Mb proximal to the NF1 gene. The telomeric deletion boundary is located in a single copy segment between an AT-rich segment and an AluSx-element in intron 15 of the JJAZ1 gene. Structural analysis implies that non-B DNA conformations at the breakpoints destabilized the duplex DNA and caused double-strand breaks. Although the breakpoints of this 2-Mb deletion are not recurrent, it is conspicuous that one breakpoint is located in the JJAZ1 gene. Paralogous recombination between the JJAZ1 gene and its pseudogene causes the recurrent 1.2 Mb deletions. The genomic architecture of the NF1 gene region, influenced by paralogous sequences such as the JJAZ1 gene and its pseudogene, seems also to stimulate the occurrence of non-recurrent deletions mediated by non-homologous end joining. Patient 442 described here suffers from a very high burden of subdermal neurofibromas. Magnetic resonance imaging of the whole body revealed numerous internal tumors, mainly plexiform neurofibromas and spinal tumors. This demonstrates the value of whole-body MRI scanning in determining the total tumor load, which is an important aspect in genotype/phenotype correlations with regard to large NF1 deletions.
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15
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Familial Neurofibromatosis-1 and Gilbert Syndrome. Dermatol Surg 2003. [DOI: 10.1097/00042728-200307000-00016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Kocer U, Uysal A, Sungur N, Karaaslan O, Kankaya Y, Tiftikcioglu Y. Familial neurofibromatosis-1 and Gilbert syndrome. Dermatol Surg 2003; 29:759-65. [PMID: 12828702 DOI: 10.1046/j.1524-4725.2003.29192.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Neurofibromatosis (NF) is a genetic disorder of the neural sheet, affecting almost all organ systems. METHOD A family that consisted of the father and his three children, two males and one female, having NF-1 is evaluated in detail for cosmetic purposes. The routine preoperative laboratory examinations, including complete blood counts, serum biochemistries, urinary analysis, extremity and chest roentgenograms, ultrasounds of the abdomen and the affected regions, and pelvic computed tomographies, revealed characteristics of NF-1 and unexpected hyperbilirubinemia. The patients are evaluated further for the cause of hyperbilirubinemia by the fasting test. Variously localized plexiform neurofibromas of the three children are totally excised. RESULTS The father was affected as a result of a mutation, and his three children had inherited the disease. The father, having subcutaneous neurofibromas, differs from the children, as they have elephantiasis neurofibromatosa. The children had various rare clinical presentations besides disfiguring deformities. Two male patients had retroperitoneal neurofibromas, and one had splenomegaly and osseous changes. Gilbert's disease was diagnosed, interestingly, and coincidentally in the three patients with elephantiasis due to NF-1. DISCUSSION An interesting diagnosis of NF occurring coincidentally with Gilbert's disease in a family is reported. This clinical study is the first report of Gilbert's disease accompanying familial NF.
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Affiliation(s)
- Ugur Kocer
- Department of Plastic and Reconstructive Surgery, Ankara Training and Research Hospital, Ankara, Türkiye
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17
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Abstract
Neurofibromatosis 1 occurs in 2 to 3 people per 10,000. The most frequent clinical features are café-au-lait macules, neurofibromas, intertriginous freckling, Lisch nodules, and learning disabilities, but optic and other gliomas, malignant peripheral nerve sheath tumors, and characteristic osseous lesions also can be present. Two striking aspects of neurofibromatosis 1 are its progressive nature and its extreme variability. This article reviews the natural history and some important clinical manifestations of neurofibromatosis 1, with emphasis on features that constitute the standard diagnostic criteria. The pathogenic implications of these clinical manifestations are also considered.
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Affiliation(s)
- J M Friedman
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
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