1
|
de Castro VF, Mattos D, de Carvalho FM, Cavalcanti DP, Duenas-Roque MM, Llerena J, Cosentino VR, Honjo RS, Leite JCL, Sanseverino MT, de Souza MPA, Bernardi P, Bolognese AM, Santana da Silva LC, Barbero P, Correia PS, Bueno LSM, Savastano CP, Orioli IM. New SHH and Known SIX3 Variants in a Series of Latin American Patients with Holoprosencephaly. Mol Syndromol 2021; 12:219-233. [PMID: 34421500 DOI: 10.1159/000515044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 02/04/2021] [Indexed: 11/19/2022] Open
Abstract
Holoprosencephaly (HPE) is the failure of the embryonic forebrain to develop into 2 hemispheres promoting midline cerebral and facial defects. The wide phenotypic variability and causal heterogeneity make genetic counseling difficult. Heterozygous variants with incomplete penetrance and variable expressivity in the SHH, SIX3, ZIC2, and TGIF1 genes explain ∼25% of the known causes of nonchromosomal HPE. We studied these 4 genes and clinically described 27 Latin American families presenting with nonchromosomal HPE. Three new SHH variants and a third known SIX3 likely pathogenic variant found by Sanger sequencing explained 15% of our cases. Genotype-phenotype correlation in these 4 families and published families with identical or similar driver gene, mutated domain, conservation of residue in other species, and the type of variant explain the pathogenicity but not the phenotypic variability. Nine patients, including 2 with SHH pathogenic variants, presented benign variants of the SHH, SIX3, ZIC2, and TGIF1 genes with potential alteration of splicing, a causal proposition in need of further studies. Finding more families with the same SIX3 variant may allow further identification of genetic or environmental modifiers explaining its variable phenotypic expression.
Collapse
Affiliation(s)
- Viviane Freitas de Castro
- ECLAMC at Departamento de Genética, UFRJ, Rio de Janeiro, Brazil.,Instituto Nacional de Genética Médica Populacional INAGEMP, Porto Alegre, Brazil
| | - Daniel Mattos
- ECLAMC at Departamento de Genética, UFRJ, Rio de Janeiro, Brazil.,Instituto Nacional de Genética Médica Populacional INAGEMP, Porto Alegre, Brazil
| | - Flavia Martinez de Carvalho
- Instituto Nacional de Genética Médica Populacional INAGEMP, Porto Alegre, Brazil.,ECLAMC at Laboratorio Epidemiol. Malformações Congênitas, IOC/FIOCRUZ, Rio de Janeiro, Brazil
| | | | - Milagros M Duenas-Roque
- ECLAMC at Servicio de Genética, Hospital Nacional Edgardo Rebagliati Martins/EsSalud, Lima, Peru
| | - Juan Llerena
- Instituto Nacional de Genética Médica Populacional INAGEMP, Porto Alegre, Brazil.,ECLAMC at Centro de Genética Médica, IFF/FIOCRUZ, Rio de Janeiro, Brazil
| | | | | | | | | | | | - Pricila Bernardi
- Núcleo de Genética Clínica, Departamento de Clínica Médica/UFSC, Florianópolis, Brazil
| | - Ana Maria Bolognese
- Departamento de Ortodontia, Faculdade de Odontologia/UFRJ, Rio de Janeiro, Brazil
| | - Luiz Carlos Santana da Silva
- Instituto Nacional de Genética Médica Populacional INAGEMP, Porto Alegre, Brazil.,Laboratório de Erros Inatos de Metabolismo, Instituto de Ciências Biológicas/UFP, Belém, Brazil
| | - Pablo Barbero
- RENAC, Centro Nacional de Genética Médica Dr. Eduardo E. Castilla/MS, Buenos Aires, Argentina
| | | | | | | | - Iêda Maria Orioli
- ECLAMC at Departamento de Genética, UFRJ, Rio de Janeiro, Brazil.,Instituto Nacional de Genética Médica Populacional INAGEMP, Porto Alegre, Brazil
| |
Collapse
|
2
|
Hong S, Hu P, Jang JH, Carrington B, Sood R, Berger SI, Roessler E, Muenke M. Functional analysis of Sonic Hedgehog variants associated with holoprosencephaly in humans using a CRISPR/Cas9 zebrafish model. Hum Mutat 2020; 41:2155-2166. [PMID: 32939873 DOI: 10.1002/humu.24119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 08/17/2020] [Accepted: 09/12/2020] [Indexed: 01/20/2023]
Abstract
Genetic variation in the highly conserved Sonic Hedgehog (SHH) gene is one of the most common genetic causes for the malformations of the brain and face in humans described as the holoprosencephaly clinical spectrum. However, only a minor fraction of known SHH variants have been experimentally proven to lead to abnormal function. Employing a phenotypic rescue assay with synthetic human messenger RNA variant constructs in shha-/- knockout zebrafish, we evaluated 104 clinically reported in-frame and missense SHH variants. Our data helped us to classify them into loss of function variants (31), hypomorphic variants (33), and nonpathogenic variants (40). We discuss the strengths and weaknesses of currently accepted predictors of variant deleteriousness and the American College of Medical Genetics and Genomics guidelines for variant interpretation in the context of this functional model; furthermore, we demonstrate the robustness of model systems such as zebrafish as a rapid method to resolve variants of uncertain significance.
Collapse
Affiliation(s)
- Sungkook Hong
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Ping Hu
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jae Hee Jang
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA.,College of Computer, Mathematical, and Natural Sciences, University of Maryland, College Park, Maryland, USA
| | - Blake Carrington
- Zebrafish Core, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Raman Sood
- Zebrafish Core, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Seth I Berger
- Children's National Hospital, Center for Genetic Medicine Research and Rare Disease Institute, Washington DC, USA
| | - Erich Roessler
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Maximilian Muenke
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA.,American College of Medical Genetics and Genomics, Bethesda, Maryland, USA
| |
Collapse
|
3
|
Abstract
In vertebrate hedgehog signaling, hedgehog ligands are processed to become bilipidated and then multimerize, which allows them to leave the signaling cell via Dispatched 1 and become transported via glypicans and megalin to the responding cells. Hedgehog then interacts with a complex of Patched 1 and Cdo/Boc, which activates endocytic Smoothened to the cilium. Patched 1 regulates the activity of Smoothened (1) via Vitamin D3, which inhibits Smoothened in the absence of hedgehog ligand or (2) via oxysterols, which activate Smoothened in the presence of hedgehog ligand. Hedgehog ligands also interact with Hip1, Patched 2, and Gas1, which regulate the range as well as the level of hedgehog signaling. In vertebrates, Smoothened is shortened at its C-terminal end and lacks most of the phosphorylation sites of importance in Drosophila. Cos2, also of importance in Drosophila, plays no role in mammalian transduction, nor do its homologs Kif7 and Kif27. The cilium may provide a function analogous to that of Cos2 by linking Smoothened to the modulation of Gli transcription factors. Disorders associated with the hedgehog signaling network follow, including nevoid basal cell carcinoma syndrome, holoprosencephaly, Smith-Lemli-Opitz syndrome, Greig cephalopolysyndactyly syndrome, Pallister-Hall syndrome, Carpenter syndrome, and Rubinstein-Taybi syndrome.
Collapse
Affiliation(s)
- M Michael Cohen
- Department of Pediatrics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
| |
Collapse
|
4
|
Paulussen ADC, Schrander-Stumpel CT, Tserpelis DCJ, Spee MKM, Stegmann APA, Mancini GM, Brooks AS, Collée M, Maat-Kievit A, Simon MEH, van Bever Y, Stolte-Dijkstra I, Kerstjens-Frederikse WS, Herkert JC, van Essen AJ, Lichtenbelt KD, van Haeringen A, Kwee ML, Lachmeijer AMA, Tan-Sindhunata GMB, van Maarle MC, Arens YHJM, Smeets EEJGL, de Die-Smulders CE, Engelen JJM, Smeets HJ, Herbergs J. The unfolding clinical spectrum of holoprosencephaly due to mutations in SHH, ZIC2, SIX3 and TGIF genes. Eur J Hum Genet 2010; 18:999-1005. [PMID: 20531442 PMCID: PMC2987413 DOI: 10.1038/ejhg.2010.70] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 03/23/2010] [Accepted: 03/25/2010] [Indexed: 11/09/2022] Open
Abstract
Holoprosencephaly is a severe malformation of the brain characterized by abnormal formation and separation of the developing central nervous system. The prevalence is 1:250 during early embryogenesis, the live-born prevalence is 1:16 000. The etiology of HPE is extremely heterogeneous and can be teratogenic or genetic. We screened four known HPE genes in a Dutch cohort of 86 non-syndromic HPE index cases, including 53 family members. We detected 21 mutations (24.4%), 3 in SHH, 9 in ZIC2 and 9 in SIX3. Eight mutations involved amino-acid substitutions, 7 ins/del mutations, 1 frame-shift, 3 identical poly-alanine tract expansions and 2 gene deletions. Pathogenicity of mutations was presumed based on de novo character, predicted non-functionality of mutated proteins, segregation of mutations with affected family-members or combinations of these features. Two mutations were reported previously. SNP array confirmed detected deletions; one spanning the ZIC2/ZIC5 genes (approx. 100 kb) the other a 1.45 Mb deletion including SIX2/SIX3 genes. The mutation percentage (24%) is comparable with previous reports, but we detected significantly less mutations in SHH: 3.5 vs 10.7% (P=0.043) and significantly more in SIX3: 10.5 vs 4.3% (P=0.018). For TGIF1 and ZIC2 mutation the rate was in conformity with earlier reports. About half of the mutations were de novo, one was a germ line mosaic. The familial mutations displayed extensive heterogeneity in clinical manifestation. Of seven familial index patients only two parental carriers showed minor HPE signs, five were completely asymptomatic. Therefore, each novel mutation should be considered as a risk factor for clinically manifest HPE, with the caveat of reduced clinical penetrance.
Collapse
Affiliation(s)
- Aimée D C Paulussen
- Department of Clinical Genetics, School for Oncology & Developmental Biology (GROW), Maastricht UMC, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Roessler E, El-Jaick KB, Dubourg C, Vélez JI, Solomon BD, Pineda-Álvarez DE, Lacbawan F, Zhou N, Ouspenskaia M, Paulussen A, Smeets HJ, Hehr U, Bendavid C, Bale S, Odent S, David V, Muenke M. The mutational spectrum of holoprosencephaly-associated changes within the SHH gene in humans predicts loss-of-function through either key structural alterations of the ligand or its altered synthesis. Hum Mutat 2009; 30:E921-35. [PMID: 19603532 PMCID: PMC2772877 DOI: 10.1002/humu.21090] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mutations within either the SHH gene or its related pathway components are the most common, and best understood, pathogenetic changes observed in holoprosencephaly patients; this fact is consistent with the essential functions of this gene during forebrain development and patterning. Here we summarize the nature and types of deleterious sequence alterations among over one hundred distinct mutations in the SHH gene (64 novel mutations) and compare these to over a dozen mutations in disease-related Hedgehog family members IHH and DHH. This combined structural analysis suggests that dysfunction of Hedgehog signaling in human forebrain development can occur through truncations or major structural changes to the signaling domain, SHH-N, as well as due to defects in the processing of the mature ligand from its pre-pro-precursor or defective post-translation bi-lipid modifications with palmitate and cholesterol.
Collapse
Affiliation(s)
- Erich Roessler
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Kenia B. El-Jaick
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Christèle Dubourg
- Laboratoire de Génétique Moléculaire, CHU Pontchaillou, Rennes Cedex, France
- CNRS UMR6061 Génétique et Développement, Université de Rennes 1, IFR140, France
| | - Jorge I. Vélez
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Benjamin D. Solomon
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Daniel E. Pineda-Álvarez
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Felicitas Lacbawan
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Nan Zhou
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Maia Ouspenskaia
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Aimée Paulussen
- Academic Hospital and Department of Clinical Genetics, University of Maastricht, the Netherlands
| | - Hubert J. Smeets
- Academic Hospital and Department of Clinical Genetics, University of Maastricht, the Netherlands
| | - Ute Hehr
- Center for Human Genetics and Department of Human Genetics, University of Regensburg, Germany
| | - Claude Bendavid
- Laboratoire de Génétique Moléculaire, CHU Pontchaillou, Rennes Cedex, France
- CNRS UMR6061 Génétique et Développement, Université de Rennes 1, IFR140, France
| | | | - Sylvie Odent
- CNRS UMR6061 Génétique et Développement, Université de Rennes 1, IFR140, France
- Service de génétique clinique,CHU Hôpital Sud, Rennes, France
| | - Véronique David
- Laboratoire de Génétique Moléculaire, CHU Pontchaillou, Rennes Cedex, France
- CNRS UMR6061 Génétique et Développement, Université de Rennes 1, IFR140, France
| | - Maximilian Muenke
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| |
Collapse
|
6
|
El-Jaick KB, Fonseca RF, Moreira MA, Ribeiro MG, Bolognese AM, Dias SO, Pereira ET, Castilla EE, Orioli IM. Single median maxillary central incisor: new data and mutation review. BIRTH DEFECTS RESEARCH. PART A, CLINICAL AND MOLECULAR TERATOLOGY 2007; 79:573-80. [PMID: 17584896 DOI: 10.1002/bdra.20380] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Single median maxillary central incisor (SMMCI) is a rare anomaly that may occur alone or associated with other conditions, frequently as part of the holoprosencephaly (HPE) spectrum. However, it has been suggested that SMMCI alone, or associated with some midline defects, may be considered a different entity from HPE (OMIM: 147250). Families with SMMCI, without HPE cases, are difficult to counsel for the risk of HPE in future generations because the same midline defects described as part of the "SMMCI syndrome" can also be part of the HPE spectrum. METHODS We screened five cases of SMMCI for mutations in three HPE genes, SHH, TGIF, and SIX3. RESULTS A missense mutation c.686C>T was found in the gene SIX3 of one patient, which did not differ from the accepted 20% of known HPE gene mutations among all HPE cases. Our results and an extensive literature review of gene mutations in patients with SMMCI showed that 27/28 of them were in HPE genes: SHH (n = 21), SIX3 (n = 3), TGIF (n = 1), GLI2 (n = 1), and PTCH (n = 1), and only one in the SALL4 gene. CONCLUSIONS The clinical findings in patients with SMMCI without HPE in families with mutations in HPE genes cannot be distinguished from the findings reported in the SMMCI syndrome. Therefore, persons with SMMCI and their relatives should be carefully investigated for related midline disorders, especially of the HPE spectrum, and all known HPE genes screened.
Collapse
Affiliation(s)
- Kênia B El-Jaick
- Estudo Latino Americano de Malformações Congênitas, Departamento de Genética, Universidade Federal do Rio de Janeiro, Brazil
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Cohen MM. Holoprosencephaly: clinical, anatomic, and molecular dimensions. BIRTH DEFECTS RESEARCH. PART A, CLINICAL AND MOLECULAR TERATOLOGY 2006; 76:658-73. [PMID: 17001700 DOI: 10.1002/bdra.20295] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Holoprosencephaly is addressed under the following headings: alobar, semilobar, and lobar holoprosencephaly; arrhinencephaly; agenesis of the corpus callosum; pituitary abnormalities; hindbrain abnormalities; syntelencephaly; aprosencephaly/atelencephaly; neural tube defects; facial anomalies; median cleft lip; minor facial anomalies; single maxillary central incisor; holoprosencephaly-like phenotype; epidemiology; genetic causes of holoprosencephaly; teratogenic causes of holoprosencephaly; SHH mutations; ZIC2 mutations; SIX3 mutations; TGIF mutations; PTCH mutations; GLI2 mutations; FAST1 mutations; TDGF1 mutations; and DHCR7 mutations.
Collapse
Affiliation(s)
- M Michael Cohen
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada.
| |
Collapse
|