1
|
Park J, Jeon M, Maeng S, Kwon DK, Kim S, Lee JE. Central precocious puberty with hypothalamic hamartoma: the first case reports of 2 siblings with different phenotypes of Seckel syndrome 5. Ann Pediatr Endocrinol Metab 2023; 28:225-230. [PMID: 35798296 PMCID: PMC10556446 DOI: 10.6065/apem.2244066.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/01/2022] [Accepted: 05/11/2022] [Indexed: 11/20/2022] Open
Abstract
Hypothalamic hamartomas (HHs) are nonneoplastic mass lesions located in the hypothalamus that can cause central precocious puberty (CPP) and/or gelastic seizures. Seckel syndrome 5 (OMIM210600, SCKL5) is a rare autosomal recessive genetic spectrum disorder characterized by intrauterine growth retardation, proportionate osteodysplastic primordial dwarfism, a wide range of intellectual disability, "bird-headed" facial features, and microcephaly with various structural brain abnormalities. Two siblings presented with short stature and small head circumference and were diagnosed with SCKL 5. The younger sister had HH with CPP and experienced a slipped capital femoral epiphysis during treatment. The 2 siblings had the same genetic variant but showed different phenotypes, which has not been reported previously; this study also as presents the first cases of SCKL5 diagnosed by genetic confirmation in Korea.
Collapse
Affiliation(s)
- Jisun Park
- Department of Pediatrics, Inha University Hospital, Incheon, Korea
| | - Minjun Jeon
- Department of Pediatrics, Inha University Hospital, Incheon, Korea
| | - Seri Maeng
- Department of Psychiatry, Inha University Hospital, Incheon, Korea
| | - Dae Kyu Kwon
- Department of Orthopedics, Inha University Hospital, Incheon, Korea
| | - Sujin Kim
- Department of Pediatrics, Inha University Hospital, Incheon, Korea
| | - Ji Eun Lee
- Department of Pediatrics, Inha University Hospital, Incheon, Korea
| |
Collapse
|
2
|
Halperin D, Agam N, Hallak M, Feinstein M, Drabkin M, Yogev Y, Wormser O, Shavit E, Gradstein L, Shelef I, Mijalovsky A, Flusser H, Birk OS. A syndrome of severe intellectual disability, hypotonia, failure to thrive, dysmorphism, and thinning of corpus callosum maps to chromosome 7q21.13-q21.3. Clin Genet 2022; 102:123-129. [PMID: 35443069 PMCID: PMC9545274 DOI: 10.1111/cge.14143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 04/13/2022] [Accepted: 04/16/2022] [Indexed: 11/28/2022]
Abstract
Six individuals of consanguineous Bedouin kindred presented at infancy with an autosomal recessive syndrome of severe global developmental delay, positive pyramidal signs, unique dysmorphism, skeletal abnormalities, and severe failure to thrive with normal birth weights. Patients had a profound intellectual disability and cognitive impairment with almost no acquired developmental milestones by 12 months. Early‐onset axial hypotonia evolved with progressive muscle weakness, reduced muscle tone, and hyporeflexia. Craniofacial dysmorphism consisted of a triangular face with a prominent forehead and midface hypoplasia. Magnetic resonance imaging (MRI) demonstrated thinning of the corpus callosum and paucity of white matter. Genome‐wide linkage analysis identified a single ~4 Mbp disease‐associated locus on chromosome 7q21.13‐q21.3 (LOD score>5). Whole‐exome and genome sequencing identified no nonsynonymous pathogenic biallelic variants in any of the genes within this locus. Following the exclusion of partially resembling syndromes, we now describe a novel autosomal recessive syndrome mapped to a ~4Mbp locus on chromosome 7.
Collapse
Affiliation(s)
- Daniel Halperin
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Nadav Agam
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Maher Hallak
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Miora Feinstein
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Max Drabkin
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yuval Yogev
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ohad Wormser
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Eitan Shavit
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Libe Gradstein
- Department of Ophthalmology, Soroka University Medical Center and Clalit Health Services, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ilan Shelef
- Department of Imaging, Soroka University Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Aanalia Mijalovsky
- Zusman Child Development Center, Division of Pediatrics, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Hagit Flusser
- Zusman Child Development Center, Division of Pediatrics, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Ohad S Birk
- The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Genetics Institute, Soroka University Medical Center, Beer-Sheva, Israel
| |
Collapse
|
3
|
Cardiovascular anomalies in Seckel syndrome: report of two patients and review of the literature. Cardiol Young 2022; 32:487-490. [PMID: 34387179 DOI: 10.1017/s1047951121003097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Seckel syndrome is a very rare autosomal recessive disorder also known as bird headed dwarfism". It is characterised by proportional short stature, low birth weight, dysmorphic facial appearance, and mental retardation. In addition to its dysmorphic features, skeletal, endocrine, gastrointestinal, haematologic, genitourinary, and nervous system has been involved. Cardiovascular features very rarely associate with Seckel syndrome. We report two patients with Seckel syndrome, one with dilated cardiomyopathy and the other with multiple ventricular septal defects. Dilated cardiomyopathy and isolated ventricular septal defect have not been previously reported in Seckel syndrome. Cardiovascular evaluation should be performed in all patients with Seckel syndrome. Early diagnosis of congenital and acquired heart diseases will reduce morbidity and mortality in these patients.
Collapse
|
4
|
Tingler M, Philipp M, Burkhalter MD. DNA Replication proteins in primary microcephaly syndromes. Biol Cell 2022; 114:143-159. [PMID: 35182397 DOI: 10.1111/boc.202100061] [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: 08/19/2021] [Revised: 01/28/2022] [Accepted: 01/31/2022] [Indexed: 11/30/2022]
Abstract
SCOPE Improper expansion of neural stem and progenitor cells during brain development manifests in primary microcephaly. It is characterized by a reduced head circumference, which correlates with a reduction in brain size. This often corresponds to a general underdevelopment of the brain and entails cognitive, behavioral and motoric retardation. In the past decade significant research efforts have been undertaken to identify genes and the molecular mechanisms underlying microcephaly. One such gene set encompasses factors required for DNA replication. Intriguingly, a growing body of evidence indicates that a substantial number of these genes mediate faithful centrosome and cilium function in addition to their canonical function in genome duplication. Here, we summarize, which DNA replication factors are associated with microcephaly syndromes and to which extent they impact on centrosomes and cilia. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Melanie Tingler
- Department of Experimental and Clinical Pharmacology and Pharmacogenomics, Section of Pharmacogenomics, Eberhard-Karls-University Tübingen, Tübingen, 72074, Germany
| | - Melanie Philipp
- Department of Experimental and Clinical Pharmacology and Pharmacogenomics, Section of Pharmacogenomics, Eberhard-Karls-University Tübingen, Tübingen, 72074, Germany
| | - Martin D Burkhalter
- Department of Experimental and Clinical Pharmacology and Pharmacogenomics, Section of Pharmacogenomics, Eberhard-Karls-University Tübingen, Tübingen, 72074, Germany
| |
Collapse
|
5
|
Khojah O, Alamoudi S, Aldawsari N, Babgi M, Lary A. Central nervous system vasculopathy and Seckel syndrome: case illustration and systematic review. Childs Nerv Syst 2021; 37:3847-3860. [PMID: 34345934 PMCID: PMC8604825 DOI: 10.1007/s00381-021-05284-8] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 06/30/2021] [Indexed: 11/05/2022]
Abstract
PURPOSE To systematically review reported cases of Seckel syndrome (SS) and point out cases associated with central nervous system (CNS) vasculopathy and provide a summary of their clinical presentation, management, and outcomes including our illustrative case. METHODS We conducted a search on the MEDLINE, PubMed, Google Scholar, and Cochrane databases using the keywords "Seckel + syndrome." We identified 127 related articles reporting 252 cases of SS apart from our case. Moreover, we searched for SS cases with CNS vasculopathies from the same databases. We identified 7 related articles reporting 7 cases of CNS vasculopathies in SS patients. RESULTS The overall rate of CNS vasculopathy in SS patients is 3.16% (n = 8/253), where moyamoya disease (MMD) accounted for 1.97%. The mean age is 13.5 years (6-19 years), with equal gender distribution (M:F, 1:1). The most common presenting symptoms were headache and seizure followed by weakness or coma. Aneurysms were mostly located in the basilar artery, middle cerebral artery, and internal carotid artery, respectively. Regardless of the management approach, 50% of the cases sustained mild-moderate neurological deficit, 37.5% have died, and 12.5% sustained no deficit. CONCLUSION A high index of suspicion should be maintained in (SS) patients, and MMD should be part of the differential diagnosis. Prevalence of CNS vasculopathy in SS is 3.16% with a much higher prevalence of MMD compared to the general population. Screening for cerebral vasculopathy in SS is justifiable especially in centers that have good resources. Further data are still needed to identify the most appropriate management plan in these cases.
Collapse
Affiliation(s)
- Osama Khojah
- College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia.
- King Abdullah International Medical Research Center, Jeddah, Saudi Arabia.
| | - Saeed Alamoudi
- College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia
- King Abdullah International Medical Research Center, Jeddah, Saudi Arabia
| | - Nouf Aldawsari
- King Abdulaziz Medical City, National Guard Health Affairs, Jeddah, Saudi Arabia
| | - Mohammed Babgi
- College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia
- Division of Neurosurgery, King Abdulaziz University Hospital, Jeddah, Saudi Arabia
| | - Ahmed Lary
- College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia
- King Abdullah International Medical Research Center, Jeddah, Saudi Arabia
- King Abdulaziz Medical City, National Guard Health Affairs, Jeddah, Saudi Arabia
| |
Collapse
|
6
|
Saeidi M, Shahbandari M. A Child with Seckel Syndrome and Arterial Stenosis: Case Report and Literature Review. Int Med Case Rep J 2020; 13:159-163. [PMID: 32523383 PMCID: PMC7234957 DOI: 10.2147/imcrj.s241601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/02/2020] [Indexed: 01/05/2023] Open
Abstract
Background Seckel syndrome is a rare genetic disorder with autosomal recessive inheritance. It is characterized by dysmorphic features, intrauterine and postnatal growth restriction, microcephaly and mental retardation. Although cardiovascular complications are not prevalent in this syndrome, severe sinus bradycardia, hypertension and brain vasculopathy are reported. Here, for the first time, we describe a case of lower extremity arterial occlusion in a case of Seckel syndrome. Case Presentation An 8-year-old girl with the characteristic features of Seckel syndrome was admitted to the children's hospital with the complaint of left lower extremity pain and a deep ulcer on her left shin. On examination, the left extremity was cooler than the other side, with a bluish color. Dorsalis pedis and popliteal artery pulses were not palpable on the left. A wound measuring 3 by 5 cm with gangrenous margins was visible on the anterior surface of the left leg. Severe stenosis in the left superficial femoral artery was reported on angiography. Considering the lean body of the patient, angioplasty was not possible and conservative wound care, analgesic drugs and aspirin were recommended. Conclusion Clinicians should be suspicious of vascular complications in patients with Seckel syndrome, even in the absence of any other risk factors.
Collapse
Affiliation(s)
- Minoo Saeidi
- Department of Pediatrics, Imam Hossein Children Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Morteza Shahbandari
- Department of Vascular Surgery, Isfahan University of Medical Sciences, Isfahan, Iran
| |
Collapse
|
7
|
Ouattara ABI, Barro M, Nacro SF, Traoré I, Sanogo B, Diallo JW, Nacro B. The Seckel syndrome: A case observed in the pediatric department of the University Hospital Center Sourou Sanou (Burkina Faso). Pediatr Rep 2020; 12:8231. [PMID: 32308969 PMCID: PMC7160856 DOI: 10.4081/pr.2020.8231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 12/10/2019] [Indexed: 12/02/2022] Open
Abstract
Seckel syndrome-1 or "bird-headed dwarfism", Online Mendelian Inheritance in Man number 210600, is a rare genetic disease with an autosomal recessive transmission. We report a female child of 56 months diagnosed with SCKL1 at the Pediatric department of the University Hospital Center Sourou Sanou, Burkina Faso. She showed the typical features including facial dysmorphism, dwarfism, microcephalus and mental retardation. Ophthalmic and dental anomaly and extremities were associated. Without a codified etiological treatment, a psychotherapist support, a genetic counseling, a regular pediatric follow-up, a quarterly odontostomatological and ophthalmological follow- up have been recommended.
Collapse
Affiliation(s)
| | | | | | | | | | - Jean W Diallo
- Ophtalmology Department, University Hospital Center Sourou Sanou, Bobo- Dioulasso, Burkina Faso
| | | |
Collapse
|
8
|
Tarnauskaitė Ž, Bicknell LS, Marsh JA, Murray JE, Parry DA, Logan CV, Bober MB, de Silva DC, Duker AL, Sillence D, Wise C, Jackson AP, Murina O, Reijns MAM. Biallelic variants in DNA2 cause microcephalic primordial dwarfism. Hum Mutat 2019; 40:1063-1070. [PMID: 31045292 PMCID: PMC6773220 DOI: 10.1002/humu.23776] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 03/15/2019] [Accepted: 04/28/2019] [Indexed: 11/11/2022]
Abstract
Microcephalic primordial dwarfism (MPD) is a group of rare single-gene disorders characterized by the extreme reduction in brain and body size from early development onwards. Proteins encoded by MPD-associated genes play important roles in fundamental cellular processes, notably genome replication and repair. Here we report the identification of four MPD individuals with biallelic variants in DNA2, which encodes an adenosine triphosphate (ATP)-dependent helicase/nuclease involved in DNA replication and repair. We demonstrate that the two intronic variants (c.1764-38_1764-37ins(53) and c.74+4A>C) found in these individuals substantially impair DNA2 transcript splicing. Additionally, we identify a missense variant (c.1963A>G), affecting a residue of the ATP-dependent helicase domain that is highly conserved between humans and yeast, with the resulting substitution (p.Thr655Ala) predicted to directly impact ATP/ADP (adenosine diphosphate) binding by DNA2. Our findings support the pathogenicity of these variants as biallelic hypomorphic mutations, establishing DNA2 as an MPD disease gene.
Collapse
Affiliation(s)
- Žygimantė Tarnauskaitė
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| | - Louise S. Bicknell
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| | - Joseph A. Marsh
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| | - Jennie E. Murray
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| | - David A. Parry
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| | - Clare V. Logan
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| | - Michael B. Bober
- Division of Genetics, Department of PediatricsNemours/Alfred I. duPont Hospital for ChildrenWilmingtonDelaware
| | - Deepthi C. de Silva
- Department of Physiology, Faculty of MedicineUniversity of KelaniyaColomboSri Lanka
| | - Angela L. Duker
- Division of Genetics, Department of PediatricsNemours/Alfred I. duPont Hospital for ChildrenWilmingtonDelaware
| | - David Sillence
- Discipline of Genomic Medicine, Faculty of Medicine and HealthUniversity of SydneySydneyAustralia
- Western Sydney Genetics ProgramSydney Children's Hospitals NetworkWestmeadAustralia
| | - Carol Wise
- Sarah M. and Charles E. Seay Center for Musculoskeletal ResearchTexas Scottish, Rite Hospital for ChildrenDallasTexas
- McDermott Center for Human Growth and DevelopmentUniversity of Texas, Southwestern Medical CenterDallasTexas
- Department of Orthopaedic SurgeryUniversity of Texas Southwestern Medical CenterDallasTexas
- Department of PediatricsUniversity of Texas Southwestern Medical CenterDallasTexas
| | - Andrew P. Jackson
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| | - Olga Murina
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| | - Martin A. M. Reijns
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular MedicineUniversity of EdinburghEdinburghUnited Kingdom
| |
Collapse
|
9
|
Akkurt MO, Pakay K, Akkurt I, Temur M, Korkmazer E. Prenatal diagnosis of Seckel syndrome at 21 weeks' gestation and review of the literature. J Matern Fetal Neonatal Med 2017; 32:1905-1908. [PMID: 29284336 DOI: 10.1080/14767058.2017.1419467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND The Seckel syndrome is an autosomal recessive inherited disorder that characterized severe pre- and post-natal growth restriction, microcephaly and a bird-like fetal head appearance. A few clinical reports revealed prenatal sonographic findings in the literature. CASE A 29-year-old, Turkish, gravid 3, para 2, woman was referred to our center for further evaluation of a suspicion of microcephaly at 21 weeks' gestation. The couple was third degree consanguineous. Detailed 2- and 3-dimensional sonography scan revealed a bird-headed appearance, prominent eyes with hypotelorism, a severe microcephaly (bi-parietal diameter and head circumference were both < 1. Percentile for 21 weeks' gestation), a beaked nose, and increased nuchal fold thickness measurement (> 95th percentile), low-set and prominent ears. All sonographic findings suggested Seckel syndrome and the couple elected termination of pregnancy in the present case. SUMMARY Seckel syndrome should be kept in mind in the differential diagnosis of severe microcephaly, accompanied by fetal growth restriction. 3D ultrasound is a useful adjuvant to routine 2D sonography for prenatal diagnosis of the syndrome and can delineate abnormal fetal head appearance (a bird-headed profile).
Collapse
Affiliation(s)
- Mehmet Ozgur Akkurt
- a Department of Obstetrics and Gynecology , Bursa Yuksek Ihtisas Training and Research Hospital , Bursa , Turkey
| | - Kaan Pakay
- a Department of Obstetrics and Gynecology , Bursa Yuksek Ihtisas Training and Research Hospital , Bursa , Turkey
| | - Iltac Akkurt
- a Department of Obstetrics and Gynecology , Bursa Yuksek Ihtisas Training and Research Hospital , Bursa , Turkey
| | - Muzaffer Temur
- a Department of Obstetrics and Gynecology , Bursa Yuksek Ihtisas Training and Research Hospital , Bursa , Turkey
| | - Engin Korkmazer
- a Department of Obstetrics and Gynecology , Bursa Yuksek Ihtisas Training and Research Hospital , Bursa , Turkey
| |
Collapse
|
10
|
Faulty RNA splicing: consequences and therapeutic opportunities in brain and muscle disorders. Hum Genet 2017; 136:1215-1235. [DOI: 10.1007/s00439-017-1802-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/13/2017] [Indexed: 12/12/2022]
|
11
|
Primordial dwarfism: overview of clinical and genetic aspects. Mol Genet Genomics 2015; 291:1-15. [PMID: 26323792 DOI: 10.1007/s00438-015-1110-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 08/21/2015] [Indexed: 01/16/2023]
Abstract
Primordial dwarfism is a group of genetic disorders which include Seckel Syndrome, Silver-Russell Syndrome, Microcephalic Osteodysplastic Primordial Dwarfism types I/III, II and Meier-Gorlin Syndrome. This genetic disorder group is characterized by intra-uterine growth retardation and post-natal growth abnormalities which occur as a result of disorganized molecular and genomic changes in embryonic stage and, thus, it represents a unique area to study growth and developmental abnormalities. Lot of research has been carried out on different aspects; however, a consolidated review that discusses an overall spectrum of this disorder is not accessible. Recent research in this area points toward important molecular and cellular mechanisms in human body that regulate the complexity of growth process. Studies have emerged that have clearly associated with a number of abnormal chromosomal, genetic and epigenetic alterations that can predispose an embryo to develop PD-associated developmental defects. Finding and associating such fundamental changes to its subtypes will help in re-examination of alleged functions at both cellular and developmental levels and thus reveal the intrinsic mechanism that leads to a balanced growth. Although such findings have unraveled a subtle understanding of growth process, we further require active research in terms of identification of reliable biomarkers for different subtypes as an immediate requirement for clinical utilization. It is hoped that further study will advance the understanding of basic mechanisms regulating growth relevant to human health. Therefore, this review has been written with an aim to present an overview of chromosomal, molecular and epigenetic modifications reported to be associated with different subtypes of this heterogenous disorder. Further, latest findings with respect to clinical and molecular genetics research have been summarized to aid the medical fraternity in their clinical utility, for diagnosing disorders where there are overlapping physical attributes and simultaneously inform about the latest developments in PD biology.
Collapse
|
12
|
Ramasamy C, Satheesh S, Selvaraj R. Seckel syndrome with severe sinus bradycardia. Indian J Pediatr 2015; 82:292-3. [PMID: 25186569 DOI: 10.1007/s12098-014-1568-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 08/19/2014] [Indexed: 11/24/2022]
Abstract
Seckel syndrome is an uncommon form of microcephalic dwarfism. The authors report a young boy with Seckel syndrome who presented with severe sinus bradycardia with symptoms of syncope and presyncope. Implantation of a permanent pacemaker was necessary in view of the severe symptoms. Although uncommon, cardiac abnormalities have been rarely reported in Seckel syndrome. This is the one of the few reports of rhythm abnormalities in this condition.
Collapse
Affiliation(s)
- Chandramohan Ramasamy
- Department of Cardiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, 605006, India
| | | | | |
Collapse
|
13
|
Abstract
PURPOSE OF REVIEW To review the recent advances in the clinical and molecular characterization of primordial dwarfism, an extreme growth deficiency disorder that has its onset during embryonic development and persists throughout life. RECENT FINDINGS The last decade has witnessed an unprecedented acceleration in the discovery of genes mutated in primordial dwarfism, from one gene to more than a dozen genes. These genetic discoveries have confirmed the notion that primordial dwarfism is caused by defects in basic cellular processes, most notably centriolar biology and DNA damage response. Fortunately, the increasing number of reported clinical primordial dwarfism subtypes has been accompanied by more accurate molecular classification. SUMMARY Qualitative defects of centrioles with resulting abnormal mitosis dynamics, reduced proliferation, and increased apoptosis represent the predominant molecular pathogenic mechanism in primordial dwarfism. Impaired DNA damage response is another important mechanism, which we now know is not mutually exclusive to abnormal centrioles. Molecular characterization of primordial dwarfism is helping families by enabling more reproductive choices and may pave the way for the future development of therapeutics.
Collapse
Affiliation(s)
- Fowzan S Alkuraya
- aDepartment of Genetics, King Faisal Specialist Hospital and Research Center bDepartment of Anatomy and Cell Biology, College of Medicine, Alfasial University, Riyadh, Saudi Arabia
| |
Collapse
|
14
|
Molekulare Mechanismen des Seckel-Syndroms. MED GENET-BERLIN 2012. [DOI: 10.1007/s11825-012-0359-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Zusammenfassung
Das Seckel-Syndrom ist eine autosomal-rezessiv vererbte Erkrankung, die durch einen proportionalen, bereits bei Geburt vorhandenen Kleinwuchs, eine ausgeprägte Mikrozephalie sowie charakteristische kraniofaziale Dysmorphien gekennzeichnet ist. Patienten mit Seckel-Syndrom zeigen zusätzlich eine geistige Behinderung, und bei einigen Patienten kommt es zum frühzeitigen Auftreten altersabhängiger Erkrankungen. Genetisch betrachtet stellt das Seckel-Syndrom eine heterogene Erkrankung dar, für die in den letzten Jahren mehrere kausale Gene identifiziert werden konnten. Diese spielen auf zellulärer Ebene sowohl bei Vorgängen der Zellteilung als auch bei der Aktivierung von Schutzmechanismen nach DNA-Schädigungen eine wichtige Rolle.
Collapse
|
15
|
McIntyre RE, Lakshminarasimhan Chavali P, Ismail O, Carragher DM, Sanchez-Andrade G, Forment JV, Fu B, Del Castillo Velasco-Herrera M, Edwards A, van der Weyden L, Yang F, Ramirez-Solis R, Estabel J, Gallagher FA, Logan DW, Arends MJ, Tsang SH, Mahajan VB, Scudamore CL, White JK, Jackson SP, Gergely F, Adams DJ. Disruption of mouse Cenpj, a regulator of centriole biogenesis, phenocopies Seckel syndrome. PLoS Genet 2012; 8:e1003022. [PMID: 23166506 PMCID: PMC3499256 DOI: 10.1371/journal.pgen.1003022] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 08/23/2012] [Indexed: 02/07/2023] Open
Abstract
Disruption of the centromere protein J gene, CENPJ (CPAP, MCPH6, SCKL4), which is a highly conserved and ubiquitiously expressed centrosomal protein, has been associated with primary microcephaly and the microcephalic primordial dwarfism disorder Seckel syndrome. The mechanism by which disruption of CENPJ causes the proportionate, primordial growth failure that is characteristic of Seckel syndrome is unknown. By generating a hypomorphic allele of Cenpj, we have developed a mouse (Cenpj(tm/tm)) that recapitulates many of the clinical features of Seckel syndrome, including intrauterine dwarfism, microcephaly with memory impairment, ossification defects, and ocular and skeletal abnormalities, thus providing clear confirmation that specific mutations of CENPJ can cause Seckel syndrome. Immunohistochemistry revealed increased levels of DNA damage and apoptosis throughout Cenpj(tm/tm) embryos and adult mice showed an elevated frequency of micronucleus induction, suggesting that Cenpj-deficiency results in genomic instability. Notably, however, genomic instability was not the result of defective ATR-dependent DNA damage signaling, as is the case for the majority of genes associated with Seckel syndrome. Instead, Cenpj(tm/tm) embryonic fibroblasts exhibited irregular centriole and centrosome numbers and mono- and multipolar spindles, and many were near-tetraploid with numerical and structural chromosomal abnormalities when compared to passage-matched wild-type cells. Increased cell death due to mitotic failure during embryonic development is likely to contribute to the proportionate dwarfism that is associated with CENPJ-Seckel syndrome.
Collapse
Affiliation(s)
- Rebecca E. McIntyre
- Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Pavithra Lakshminarasimhan Chavali
- Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre and Department of Oncology, University of Cambridge, Cambridge, United Kingdom
| | - Ozama Ismail
- Mouse Genetics Project, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Damian M. Carragher
- Mouse Genetics Project, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | | | - Josep V. Forment
- The Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Beiyuan Fu
- Molecular Cytogenetics, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | | | - Andrew Edwards
- Wellcome Trust Center for Human Genetics, Oxford, United Kingdom
| | - Louise van der Weyden
- Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Fengtang Yang
- Molecular Cytogenetics, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | | | - Ramiro Ramirez-Solis
- Mouse Genetics Project, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Jeanne Estabel
- Mouse Genetics Project, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Ferdia A. Gallagher
- Department of Radiology, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Darren W. Logan
- Genetics of Instinctive Behaviour, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Mark J. Arends
- Department of Pathology, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Stephen H. Tsang
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States of America
- Bernard and Shirlee Brown Glaucoma Laboratory, Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Vinit B. Mahajan
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States of America
| | - Cheryl L. Scudamore
- Department of Pathology and Infectious Diseases, Royal Veterinary College, London, United Kingdom
| | - Jacqueline K. White
- Mouse Genetics Project, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Stephen P. Jackson
- The Gurdon Institute and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Fanni Gergely
- Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre and Department of Oncology, University of Cambridge, Cambridge, United Kingdom
| | - David J. Adams
- Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| |
Collapse
|
16
|
Müller E, Dunstheimer D, Klammt J, Friebe D, Kiess W, Kratzsch J, Kruis T, Laue S, Pfäffle R, Wallborn T, Heidemann PH. Clinical and functional characterization of a patient carrying a compound heterozygous pericentrin mutation and a heterozygous IGF1 receptor mutation. PLoS One 2012; 7:e38220. [PMID: 22693602 PMCID: PMC3365032 DOI: 10.1371/journal.pone.0038220] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Accepted: 05/01/2012] [Indexed: 11/24/2022] Open
Abstract
Intrauterine and postnatal longitudinal growth is controlled by a strong genetic component that regulates a complex network of endocrine factors integrating them with cellular proliferation, differentiation and apoptotic processes in target tissues, particularly the growth centers of the long bones. Here we report on a patient born small for gestational age (SGA) with severe, proportionate postnatal growth retardation, discreet signs of skeletal dysplasia, microcephaly and moyamoya disease. Initial genetic evaluation revealed a novel heterozygous IGF1R p.Leu1361Arg mutation affecting a highly conserved residue with the insulin-like growth factor type 1 receptor suggestive for a disturbance within the somatotropic axis. However, because the mutation did not co-segregate with the phenotype and functional characterization did not reveal an obvious impairment of the ligand depending major IGF1R signaling capabilities a second-site mutation was assumed. Mutational screening of components of the somatotropic axis, constituents of the IGF signaling system and factors involved in cellular proliferation, which are described or suggested to provoke syndromic dwarfism phenotypes, was performed. Two compound heterozygous PCNT mutations (p.[Arg585X];[Glu1774X]) were identified leading to the specification of the diagnosis to MOPD II. These investigations underline the need for careful assessment of all available information to derive a firm diagnosis from a sequence aberration.
Collapse
Affiliation(s)
- Eva Müller
- Pediatric Research Center, University Hospital for Children and Adolescents, Leipzig, Germany
| | | | - Jürgen Klammt
- Pediatric Research Center, University Hospital for Children and Adolescents, Leipzig, Germany
| | - Daniela Friebe
- Pediatric Research Center, University Hospital for Children and Adolescents, Leipzig, Germany
| | - Wieland Kiess
- Department of Pediatrics, University Hospital for Children and Adolescents, Leipzig, Germany
- * E-mail:
| | - Jürgen Kratzsch
- Institute of Laboratory Medicine and Molecular Diagnostics, Leipzig, Germany
| | - Tassilo Kruis
- Pediatric Research Center, University Hospital for Children and Adolescents, Leipzig, Germany
| | - Sandy Laue
- Pediatric Research Center, University Hospital for Children and Adolescents, Leipzig, Germany
| | - Roland Pfäffle
- Department of Pediatrics, University Hospital for Children and Adolescents, Leipzig, Germany
| | - Tillmann Wallborn
- Pediatric Research Center, University Hospital for Children and Adolescents, Leipzig, Germany
| | | |
Collapse
|
17
|
O'Driscoll M. Haploinsufficiency of DNA Damage Response Genes and their Potential Influence in Human Genomic Disorders. Curr Genomics 2011; 9:137-46. [PMID: 19440510 PMCID: PMC2679649 DOI: 10.2174/138920208784340795] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 03/31/2008] [Accepted: 03/31/2008] [Indexed: 11/22/2022] Open
Abstract
Genomic disorders are a clinically diverse group of conditions caused by gain, loss or re-orientation of a genomic region containing dosage-sensitive genes. One class of genomic disorder is caused by hemizygous deletions resulting in haploinsufficiency of a single or, more usually, several genes. For example, the heterozygous contiguous gene deletion on chromosome 22q11.2 causing DiGeorge syndrome involves at least 20-30 genes. Determining how the copy number variation (CNV) affects human variation and contributes to the aetiology and progression of various genomic disorders represents important questions for the future. Here, I will discuss the functional significance of one form of CNV, haploinsufficiency (i.e. loss of a gene copy), of DNA damage response components and its association with certain genomic disorders. There is increasing evidence that haploinsufficiency for certain genes encoding key players in the cells response to DNA damage, particularly those of the Ataxia Telangiectasia and Rad3-related (ATR)-pathway, has a functional impact. I will review this evidence and present examples of some well known clinically similar genomic disorders that have recently been shown to be defective in the ATR-dependent DNA damage response. Finally, I will discuss the potential implications of a haploinsufficiency-induced defective DNA damage response for the clinical management of certain human genomic disorders.
Collapse
Affiliation(s)
- Mark O'Driscoll
- Genome Damage & Stability Centre, University of Sussex, Falmer, Brighton, East Sussex, BN1 9RQ, UK
| |
Collapse
|
18
|
Affiliation(s)
- S Ladha
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, 980 West 28th Avenue, Vancouver, British Columbia, Canada V5Z 4H4.
| |
Collapse
|
19
|
|
20
|
Mutations in centrosomal protein CEP152 in primary microcephaly families linked to MCPH4. Am J Hum Genet 2010; 87:40-51. [PMID: 20598275 DOI: 10.1016/j.ajhg.2010.06.003] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 05/27/2010] [Accepted: 06/04/2010] [Indexed: 12/31/2022] Open
Abstract
Primary microcephaly is a rare condition in which brain size is substantially diminished without other syndromic abnormalities. Seven autosomal loci have been genetically mapped, and the underlying causal genes have been identified for MCPH1, MCPH3, MCPH5, MCPH6, and MCPH7 but not for MCPH2 or MCPH4. The known genes play roles in mitosis and cell division. We ascertained three families from an Eastern Canadian subpopulation, each with one microcephalic child. Homozygosity analysis in two families using genome-wide dense SNP genotyping supported linkage to the published MCPH4 locus on chromosome 15q21.1. Sequencing of coding exons of candidate genes in the interval identified a nonconservative amino acid change in a highly conserved residue of the centrosomal protein CEP152. The affected children in these two families were both homozygous for this missense variant. The third affected child was compound heterozygous for the missense mutation plus a second, premature-termination mutation truncating a third of the protein and preventing its localization to centrosomes in transfected cells. CEP152 is the putative mammalian ortholog of Drosphila asterless, mutations in which affect mitosis in the fly. Published data from zebrafish are also consistent with a role of CEP152 in centrosome function. By RT-PCR, CEP152 is expressed in the embryonic mouse brain, similar to other MCPH genes. Like some other MCPH genes, CEP152 shows signatures of positive selection in the human lineage. CEP152 is a strong candidate for the causal gene underlying MCPH4 and may be an important gene in the evolution of human brain size.
Collapse
|
21
|
Słabicki M, Theis M, Krastev DB, Samsonov S, Mundwiller E, Junqueira M, Paszkowski-Rogacz M, Teyra J, Heninger AK, Poser I, Prieur F, Truchetto J, Confavreux C, Marelli C, Durr A, Camdessanche JP, Brice A, Shevchenko A, Pisabarro MT, Stevanin G, Buchholz F. A genome-scale DNA repair RNAi screen identifies SPG48 as a novel gene associated with hereditary spastic paraplegia. PLoS Biol 2010; 8:e1000408. [PMID: 20613862 PMCID: PMC2893954 DOI: 10.1371/journal.pbio.1000408] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 05/19/2010] [Indexed: 12/26/2022] Open
Abstract
We have identified a novel gene in a genome-wide, double-strand break DNA repair RNAi screen and show that is involved in the neurological disease hereditary spastic paraplegia. DNA repair is essential to maintain genome integrity, and genes with roles in DNA repair are frequently mutated in a variety of human diseases. Repair via homologous recombination typically restores the original DNA sequence without introducing mutations, and a number of genes that are required for homologous recombination DNA double-strand break repair (HR-DSBR) have been identified. However, a systematic analysis of this important DNA repair pathway in mammalian cells has not been reported. Here, we describe a genome-scale endoribonuclease-prepared short interfering RNA (esiRNA) screen for genes involved in DNA double strand break repair. We report 61 genes that influenced the frequency of HR-DSBR and characterize in detail one of the genes that decreased the frequency of HR-DSBR. We show that the gene KIAA0415 encodes a putative helicase that interacts with SPG11 and SPG15, two proteins mutated in hereditary spastic paraplegia (HSP). We identify mutations in HSP patients, discovering KIAA0415/SPG48 as a novel HSP-associated gene, and show that a KIAA0415/SPG48 mutant cell line is more sensitive to DNA damaging drugs. We present the first genome-scale survey of HR-DSBR in mammalian cells providing a dataset that should accelerate the discovery of novel genes with roles in DNA repair and associated medical conditions. The discovery that proteins forming a novel protein complex are required for efficient HR-DSBR and are mutated in patients suffering from HSP suggests a link between HSP and DNA repair. All cells in our bodies have to cope with numerous lesions to their DNA. Cells use a battery of genes to repair DNA and maintain genome integrity. Given the importance of an intact genome, it is not surprising that genes with roles in DNA repair are mutated in many human diseases. Here, we present the results of a genome-scale DNA repair screen in human cells and discover 61 genes that have a potential role in this process. We studied in detail a previously uncharacterized gene (KIAA0415/SPG48) and demonstrated its importance for efficient DNA double strand break repair. Further analyses revealed mutations in the SPG48 gene in some patients with hereditary spastic paraplegia (HSP). We showed that SPG48 physically interacts with other HSP proteins and that patient cells are sensitive to DNA damaging drugs. Our data suggest a link between HSP and DNA repair and we propose that HSP patients should be screened for KIAA0415/SPG48 mutations in the future.
Collapse
Affiliation(s)
- Mikołaj Słabicki
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | - Mirko Theis
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | - Dragomir B. Krastev
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Emeline Mundwiller
- INSERM, Unit 975 Paris, France
- Université Pierre et Marie Curie-Paris6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Paris, France
- CNRS, Unité Mixte de Recherche 7225 Paris, France
| | - Magno Junqueira
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Joan Teyra
- Structural Bioinformatics, BIOTEC TU, Dresden, Germany
| | | | - Ina Poser
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Jérémy Truchetto
- INSERM, Unit 975 Paris, France
- Université Pierre et Marie Curie-Paris6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Paris, France
- CNRS, Unité Mixte de Recherche 7225 Paris, France
| | | | - Cécilia Marelli
- INSERM, Unit 975 Paris, France
- Université Pierre et Marie Curie-Paris6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Paris, France
- CNRS, Unité Mixte de Recherche 7225 Paris, France
- APHP, Pitié-Salpêtrière Hospital, Department of Genetics and Cytogenetics, Paris, France
| | - Alexandra Durr
- INSERM, Unit 975 Paris, France
- Université Pierre et Marie Curie-Paris6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Paris, France
- CNRS, Unité Mixte de Recherche 7225 Paris, France
- APHP, Pitié-Salpêtrière Hospital, Department of Genetics and Cytogenetics, Paris, France
| | | | - Alexis Brice
- INSERM, Unit 975 Paris, France
- Université Pierre et Marie Curie-Paris6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Paris, France
- CNRS, Unité Mixte de Recherche 7225 Paris, France
- APHP, Pitié-Salpêtrière Hospital, Department of Genetics and Cytogenetics, Paris, France
| | - Andrej Shevchenko
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Giovanni Stevanin
- INSERM, Unit 975 Paris, France
- Université Pierre et Marie Curie-Paris6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, Paris, France
- CNRS, Unité Mixte de Recherche 7225 Paris, France
- APHP, Pitié-Salpêtrière Hospital, Department of Genetics and Cytogenetics, Paris, France
| | - Frank Buchholz
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
- * E-mail:
| |
Collapse
|
22
|
Hall JG. Review and hypothesis: syndromes with severe intrauterine growth restriction and very short stature--are they related to the epigenetic mechanism(s) of fetal survival involved in the developmental origins of adult health and disease? Am J Med Genet A 2010; 152A:512-27. [PMID: 20101705 DOI: 10.1002/ajmg.a.33251] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Diagnosing the specific type of severe intrauterine growth restriction (IUGR) that also has post-birth growth restriction is often difficult. Eight relatively common syndromes are discussed identifying their unique distinguishing features, overlapping features, and those features common to all eight syndromes. Many of these signs take a few years to develop and the lifetime natural history of the disorders has not yet been completely clarified. The theory behind developmental origins of adult health and disease suggests that there are mammalian epigenetic fetal survival mechanisms that downregulate fetal growth, both in order for the fetus to survive until birth and to prepare it for a restricted extra-uterine environment, and that these mechanisms have long lasting effects on the adult health of the individual. Silver-Russell syndrome phenotype has recently been recognized to be related to imprinting/methylation defects. Perhaps all eight syndromes, including those with single gene mutation origin, involve the mammalian mechanism(s) of fetal survival downsizing. Insights into those mechanisms should provide avenues to understanding the natural history, the heterogeneity and possible therapy not only for these eight syndromes, but for the common adult diseases with which IUGR is associated.
Collapse
Affiliation(s)
- Judith G Hall
- Departments of Medical Genetics and Pediatrics, UBC and Children's and Women's Health Centre of British Columbia Vancouver, British Columbia, Canada.
| |
Collapse
|
23
|
Abstract
Four case records of patients with Seckel Syndrome (SS) were retrieved. Typical of bird headed dwarfism was seen in all. Chromosome 18 deletion was seen in one child with SS. MRI abnormalities were detected in 3 patients. Cytogenetic studies and neuroimaging is likely to provide important diagnostic and prognostic information.
Collapse
|
24
|
Kim TH, Kim YU, Song JG, Hwang JH. Anesthetic experience of a pediatric patient with Seckel syndrome associated with pneumonia : A case report. Korean J Anesthesiol 2009; 56:717-719. [PMID: 30625818 DOI: 10.4097/kjae.2009.56.6.717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Seckel syndrome, also called bird-headed dwarfism, is an extremely rare, inherited, autosomal recessive disorder. The patients with Seckel syndrome are characterized by growth retardation, microcephaly with mental retardation, proportional dwarfism, bird like faces, and beak-like triangular nose. A literature review reveals that they have multiple anesthetic problems such as difficult airway management, difficult venous cannulation and concomitant medical diseases. We describe our experience in anesthetic management of a 21-month-old male patient with Seckel syndrome associated with pneumonia who underwent orchiopexy for bilateral cryptochidism.
Collapse
Affiliation(s)
- Tae Hee Kim
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
| | - Young Uk Kim
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
| | - Jun Gol Song
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
| | - Jai Hyun Hwang
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
| |
Collapse
|
25
|
O'Driscoll M, Jeggo PA. The role of the DNA damage response pathways in brain development and microcephaly: insight from human disorders. DNA Repair (Amst) 2008; 7:1039-50. [PMID: 18458003 DOI: 10.1016/j.dnarep.2008.03.018] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A network of DNA damage response (DDR) mechanisms functions co-ordinately to maintain genomic stability and ensure cellular survival in the face of exogenous and endogenous DNA damage. Defects in DDR pathways have been identified in a range of human disorders, collectively classified as DDR-defective syndromes. A common feature of these syndromes is a predisposition to cancer demonstrating the importance of the DDR in cancer avoidance. How the DDR mechanisms serve to maintain genomic stability has been the predominant focus of research into their function. However, many DRR-defective syndromes are also characterised by impaired development demonstrating broader roles for the DDR mechanisms. Microcephaly, representing reduced brain size, is a feature common to a diverse range of DDR-defective disorders. Microcephaly is most likely caused by loss (increased cell death) or failure of the developing neuronal stem cells or their progenitors to divide suggesting a fundamental role for the DDR in maintaining proliferative potential in the developing nervous system. Currently, it is unclear why the DDR proteins should be more important during neuronal development compared with the development of other tissues or why the embryonic brain is more sensitive than the adult brain. Here, we overview the DDR-defective disorders in the context of microcephaly and discuss a model underlying this striking phenotype.
Collapse
Affiliation(s)
- Mark O'Driscoll
- Genome Damage and Stability Centre, University of Sussex, Brighton, East Sussex BN1 9RQ, UK.
| | | |
Collapse
|
26
|
Kulkarni A, Wilson DM. The involvement of DNA-damage and -repair defects in neurological dysfunction. Am J Hum Genet 2008; 82:539-66. [PMID: 18319069 PMCID: PMC2427185 DOI: 10.1016/j.ajhg.2008.01.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 12/17/2007] [Accepted: 01/03/2008] [Indexed: 10/22/2022] Open
Abstract
A genetic link between defects in DNA repair and neurological abnormalities has been well established through studies of inherited disorders such as ataxia telangiectasia and xeroderma pigmentosum. In this review, we present a comprehensive summary of the major types of DNA damage, the molecular pathways that function in their repair, and the connection between defective DNA-repair responses and specific neurological disease. Particular attention is given to describing the nature of the repair defect and its relationship to the manifestation of the associated neurological dysfunction. Finally, the review touches upon the role of oxidative stress, a leading precursor to DNA damage, in the development of certain neurodegenerative pathologies, such as Alzheimer's and Parkinson's.
Collapse
Affiliation(s)
- Avanti Kulkarni
- Laboratory of Molecular Gerontology, National Institute of Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - David M. Wilson
- Laboratory of Molecular Gerontology, National Institute of Aging, National Institutes of Health, Baltimore, MD 21224, USA
| |
Collapse
|
27
|
Smith JA, Nunnari G, Preuss M, Pomerantz RJ, Daniel R. Pentoxifylline suppresses transduction by HIV-1-based vectors. Intervirology 2007; 50:377-86. [PMID: 17938572 DOI: 10.1159/000109752] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Accepted: 08/02/2007] [Indexed: 12/24/2022] Open
Abstract
Pentoxifylline, a caffeine-related compound, was shown to suppress human immunodeficiency virus type 1 (HIV-1) replication. This effect is thought to be mediated by inhibition of tumor necrosis factor-alpha (TNFalpha)-mediated long-terminal repeat (LTR)-driven expression. We now demonstrate that pentoxifylline efficiently inhibits transduction by HIV-1-based vectors. This latter effect is independent of LTR-driven expression, and correlates with a reduced efficiency of the completion of the integration process in infected cells. Finally, the effect of pentoxifylline is dramatically reduced in cells expressing a dominant negative ATR protein, and in primary human cells that exhibit low level of ATR activity, suggesting that the effect of pentoxifylline on HIV-1 transduction and replication is at least partly mediated by suppression of the ATR kinase.
Collapse
Affiliation(s)
- Johanna A Smith
- Division of Infectious Diseases, Center for Human Virology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | | | | | | | | |
Collapse
|
28
|
De Coster PJ, Verbeeck RMH, Holthaus V, Martens LC, Vral A. Seckel syndrome associated with oligodontia, microdontia, enamel hypoplasia, delayed eruption, and dentin dysmineralization: a new variant? J Oral Pathol Med 2007; 35:639-41. [PMID: 17032400 DOI: 10.1111/j.1600-0714.2006.00462.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Seckel syndrome (SCKL) [OMIM Entry 210600] is a rare, autosomal recessive syndrome, characterized by severe intrauterine and postnatal growth retardation, microcephaly, mental retardation, and typical facial appearance with beaklike protrusion of the midface (bird-headed). Associated findings may include limb anomalies, dislocation of femoral heads, scoliosis, and gastrointestinal malformation. A 14-year-old boy is presented with brain hypoplasia, pachygyria, hydrocephaly, enamel hypoplasia and root dysplasia in the temporary dentition, and oligodontia, severe microdontia, and delayed eruption of the permanent dentition. The association of SCKL with the above unusual dental findings may represent a new phenotype.
Collapse
Affiliation(s)
- P J De Coster
- Department of Paediatric Dentistry and Special Care, Paecamed Research, Ghent University, Ghent, Belgium.
| | | | | | | | | |
Collapse
|
29
|
Abstract
Seckel syndrome is a very rare form of primordial dwarfism characterized by antenatal and postnatal growth delay, proportionate extreme short stature, a prominent beak-like nose, hypoplasia of the malar area, small chin, microcephaly, deformed ears lacking lobules, skeletal malformations, mental retardation, and developmental delay. This syndrome has been described with associated disorders of orthopedic, neurologic, hematologic, cardiac, and ocular systems; however, only a few reports mention dermatologic involvement. We describe a 5-year-old girl with classic Seckel syndrome who presented with moderately severe atopic dermatitis and diffuse hypopigmented macules and papules.
Collapse
Affiliation(s)
- Amy Brackeen
- Texas Tech Health Sciences Center, Department of Dermatology, 3601 4th Street STOP 9400, Lubbock, TX 79430, USA
| | | | | |
Collapse
|
30
|
Lachman RS. S. TAYBI AND LACHMAN'S RADIOLOGY OF SYNDROMES, METABOLIC DISORDERS AND SKELETAL DYSPLASIAS 2007. [PMCID: PMC7315357 DOI: 10.1016/b978-0-323-01931-6.50027-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
31
|
Pan-Hammarström Q, Lähdesmäki A, Zhao Y, Du L, Zhao Z, Wen S, Ruiz-Perez VL, Dunn-Walters DK, Goodship JA, Hammarström L. Disparate roles of ATR and ATM in immunoglobulin class switch recombination and somatic hypermutation. ACTA ACUST UNITED AC 2006; 203:99-110. [PMID: 16390936 PMCID: PMC2118080 DOI: 10.1084/jem.20050595] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Class switch recombination (CSR) and somatic hypermutation (SHM) are mechanistically related processes initiated by activation-induced cytidine deaminase. Here, we have studied the role of ataxia telangiectasia and Rad3-related protein (ATR) in CSR by analyzing the recombinational junctions, resulting from in vivo switching, in cells from patients with mutations in the ATR gene. The proportion of cells that have switched to immunoglobulin (Ig)A and IgG in the peripheral blood seems to be normal in ATR-deficient (ATRD) patients and the recombined S regions show a normal “blunt end-joining,” but impaired end joining with partially complementary (1–3 bp) DNA ends. There was also an increased usage of microhomology at the μ-α switch junctions, but only up to 9 bp, suggesting that the end-joining pathway requiring longer microhomologies (≥10 bp) may be ATR dependent. The SHM pattern in the Ig variable heavy chain genes is altered, with fewer mutations occurring at A and more mutations at T residues and thus a loss of strand bias in targeting A/T pairs within certain hotspots. These data suggest that the role of ATR is partially overlapping with that of ataxia telangiectasia–mutated protein, but that the former is also endowed with unique functional properties in the repair processes during CSR and SHM.
Collapse
Affiliation(s)
- Qiang Pan-Hammarström
- Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, SE-14186 Stockholm, Sweden.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Martin RD, Maclarnon AM, Phillips JL, Dobyns WB. Flores hominid: New species or microcephalic dwarf? ACTA ACUST UNITED AC 2006; 288:1123-45. [PMID: 17031806 DOI: 10.1002/ar.a.20389] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The proposed new hominid "Homo floresiensis" is based on specimens from cave deposits on the Indonesian island Flores. The primary evidence, dated at approximately 18,000 y, is a skull and partial skeleton of a very small but dentally adult individual (LB1). Incomplete specimens are attributed to eight additional individuals. Stone tools at the site are also attributed to H. floresiensis. The discoverers interpreted H. floresiensis as an insular dwarf derived from Homo erectus, but others see LB1 as a small-bodied microcephalic Homo sapiens. Study of virtual endocasts, including LB1 and a European microcephalic, purportedly excluded microcephaly, but reconsideration reveals several problems. The cranial capacity of LB1 ( approximately 400 cc) is smaller than in any other known hominid < 3.5 Ma and is far too small to derive from Homo erectus by normal dwarfing. By contrast, some associated tools were generated with a prepared-core technique previously unknown for H. erectus, including bladelets otherwise associated exclusively with H. sapiens. The single European microcephalic skull used in comparing virtual endocasts was particularly unsuitable. The specimen was a cast, not the original skull (traced to Stuttgart), from a 10-year-old child with massive pathology. Moreover, the calotte does not fit well with the rest of the cast, probably being a later addition of unknown history. Consideration of various forms of human microcephaly and of two adult specimens indicates that LB1 could well be a microcephalic Homo sapiens. This is the most likely explanation for the incongruous association of a small-brained recent hominid with advanced stone tools.
Collapse
Affiliation(s)
- Robert D Martin
- Academic Affairs, Field Museum, Chicago, Illinois 60605, USA.
| | | | | | | |
Collapse
|
33
|
Hall JG, Flora C, Scott CI, Pauli RM, Tanaka KI. Majewski osteodysplastic primordial dwarfism type II (MOPD II): natural history and clinical findings. Am J Med Genet A 2004; 130A:55-72. [PMID: 15368497 DOI: 10.1002/ajmg.a.30203] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A description of the clinical features of Majewski osteodysplastic primordial dwarfism type II (MOPD II) is presented based on 58 affected individuals (27 from the literature and 31 previously unreported cases). The remarkable features of MOPD II are: severe intrauterine growth retardation (IUGR), severe postnatal growth retardation; relatively proportionate head size at birth which progresses to true and disproportionate microcephaly; progressive disproportion of the short stature secondary to shortening of the distal and middle segments of the limbs; a progressive bony dysplasia with metaphyseal changes in the limbs; epiphyseal delay; progressive loose-jointedness with occasional dislocation or subluxation of the knees, radial heads, and hips; unusual facial features including a prominent nose, eyes which appear prominent in infancy and early childhood, ears which are proportionate, mildly dysplastic and usually missing the lobule; a high squeaky voice; abnormally, small, and often dysplastic or missing dentition; a pleasant, outgoing, sociable personality; and autosomal recessive inheritance. Far-sightedness, scoliosis, unusual pigmentation, and truncal obesity often develop with time. Some individuals seem to have increased susceptibility to infections. A number of affected individuals have developed dilation of the CNS arteries variously described as aneurysms and Moya Moya disease. These vascular changes can be life threatening, even in early years because of rupture, CNS hemorrhage, and strokes. There is variability between affected individuals even within the same family.
Collapse
Affiliation(s)
- Judith G Hall
- Department of Medical Genetics, UBC and Children's and Women's Health Centre of British Columbia Vancouver, British Columbia, Canada.
| | | | | | | | | |
Collapse
|
34
|
|
35
|
Alderton GK, Joenje H, Varon R, Børglum AD, Jeggo PA, O'Driscoll M. Seckel syndrome exhibits cellular features demonstrating defects in the ATR-signalling pathway. Hum Mol Genet 2004; 13:3127-38. [PMID: 15496423 DOI: 10.1093/hmg/ddh335] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To date, the only reported genetic defect identified in the developmental disorder, Seckel syndrome, is a mutation in ataxia telangiectasia and Rad3-related protein (ATR). Seckel syndrome is clinically and genetically heterogeneous and whether defects in ATR significantly contribute to Seckel syndrome is unclear. Firstly, we characterize ATR-Seckel cells for their response to DNA damage. ATR-Seckel cells display impaired phosphorylation of ATR-dependent substrates, impaired G2/M checkpoint arrest and elevated micronucleus (MN) formation following exposure to UV and agents that cause replication stalling. We describe a novel phenotype, designated nuclear fragmentation (NF), that occurs following replication arrest. Finally, we report that ATR-Seckel cells have an endogenously increased number of centrosomes in mitotic cells demonstrating a novel role for ATR in regulating centrosome stability. We exploit these phenotypes to examine cell lines derived from additional unrelated Seckel syndrome patients. We show that impaired phosphorylation of ATR-dependent substrates is a common but not invariant feature of Seckel syndrome cell lines. In contrast, all cell lines displayed defective G2/M arrest, increased levels of NF and MN formation following exposure to agents that cause replication stalling. All the Seckel syndrome cell lines examined showed increased endogenous centrosome numbers. Though ATR cDNA can complement the defects in ATR-Seckel cells, it failed to complement any of the additional cell lines. We conclude that Seckel syndrome represents a further damage response disorder that is uniquely associated with defects in the ATR-signalling pathway resulting in failed checkpoint arrest following exposure to replication fork stalling.
Collapse
Affiliation(s)
- Gemma K Alderton
- Genome Damage and Stability Centre, University of Sussex, East Sussex, BN1 9RQ, UK
| | | | | | | | | | | |
Collapse
|
36
|
O'Driscoll M, Gennery AR, Seidel J, Concannon P, Jeggo PA. An overview of three new disorders associated with genetic instability: LIG4 syndrome, RS-SCID and ATR-Seckel syndrome. DNA Repair (Amst) 2004; 3:1227-35. [PMID: 15279811 DOI: 10.1016/j.dnarep.2004.03.025] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Around 15-20 hereditary disorders associated with impaired DNA damage response mechanisms have been previously described. The range of clinical features associated with these disorders attests to the significant role that these pathways play during development. Recently, three new such disorders have been reported extending the importance of the damage response pathways to human health. LIG4 syndrome is conferred by hypomorphic mutations in DNA ligase IV, an essential component of DNA non-homologous end-joining (NHEJ), and is associated with pancytopaenia, developmental and growth delay and dysmorphic facial features. Radiosensitive severe combined immunodeficiency (RS-SCID) is caused by mutations in Artemis, a protein that plays a subsidiary role in non-homologous end-joining although it is not an essential component. RS-SCID is characterised by severe combined immunodeficiency but patients have no overt developmental abnormalities. ATR-Seckel syndrome is caused by mutations in ataxia telangiectasia and Rad3 related protein (ATR), a component of a DNA damage signalling pathway. ATR-Seckel syndrome patients have dramatic microcephaly and marked growth and developmental delay. The clinical features of these patients are considered in the light of the function of the defective protein.
Collapse
Affiliation(s)
- M O'Driscoll
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, East Sussex BN1 9RQ, UK
| | | | | | | | | |
Collapse
|
37
|
Glass RBJ, Fernbach SK, Norton KI, Choi PS, Naidich TP. The infant skull: a vault of information. Radiographics 2004; 24:507-22. [PMID: 15026597 DOI: 10.1148/rg.242035105] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The art of interpreting skull radiographs is slowly being lost as trainees in radiology see fewer plain radiographs and depend more heavily on computed tomography and magnetic resonance imaging. Nevertheless, skull radiographs still provide significant information that is helpful in finding pathologic conditions and appreciating their extents. Abnormalities in the skull may be reflected as variations in the density, size, and shape of the skull, as well as skull defects. Skeletal dysplasias may manifest as a generalized decrease in calvarial density (hypophosphatasia, osteogenesis imperfecta), a generalized increase in calvarial density (osteopetrosis), or a focal increase in density (frontometaphyseal dysplasia). Diffusely decreased or increased calvarial density is usually associated with a process that affects the entire skeleton. Therefore, correct differentiation among these dysplasias depends on other concurrent features. Decreased size of the cranial vault at birth generally implies an underlying insult to the brain, including fetal alcohol syndrome and the so-called TORCH infections (toxoplasmosis, rubella, cytomegalovirus infection, herpes simplex). Macrocephaly may result from skeletal dysplasia or an increase in the intracranial volume (eg, due to underlying anomalies of the brain such as hydrocephalus).
Collapse
Affiliation(s)
- Ronald B J Glass
- Department of Radiology, Mount Sinai Medical Center, One Gustave L. Levy Place, New York, NY 10029, USA.
| | | | | | | | | |
Collapse
|
38
|
Kilinç MO, Ninis VN, Ugur SA, Tüysüz B, Seven M, Balci S, Goodship J, Tolun A. Is the novel SCKL3 at 14q23 the predominant Seckel locus? Eur J Hum Genet 2004; 11:851-7. [PMID: 14571270 DOI: 10.1038/sj.ejhg.5201057] [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
Seckel syndrome (SCKL) is a rare disease with wide phenotypic heterogeneity. A locus (SCKL1) has been identified at 3q and another (SCKL2) at 18p, both in single kindreds afflicted with the syndrome. We report here a novel locus (SCKL3) at 14q by linkage analysis in 13 Turkish families. In total, 18 affected and 10 unaffected sibs were included in the study. Of the 10 informative families, nine with parental consanguinity and one reportedly nonconsanguineous but with two affected sibs, five were indicative of linkage to the novel locus. One of those families also linked to the SCKL1 locus. A consanguineous family with one affected sib was indicative of linkage to SCKL2. The novel gene locus SCKL3 is 1.18 cM and harbors ménage a trois 1, a gene with a role in DNA repair.
Collapse
Affiliation(s)
- Mehmet Okyay Kilinç
- Department of Molecular Biology and Genetics, Bogaziçi University, Istanbul, Turkey
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Abstract
Microcephaly is defined as a reduction in head circumference and this clinical finding infers that an individual has a significant diminution in brain volume. Microcephaly can be usefully divided into primary microcephaly, in which the brain fails to grow to the correct size during pregnancy, and secondary microcephaly, in which the brain is the expected size at birth but subsequently fails to grow normally. Current work suggests that primary microcephaly is caused by a decrease in the number of neurones generated during neurogenesis, but that in secondary microcephaly it is the number of dendritic processes and synaptic connections that is reduced. Important insights into human neurogenesis are being revealed by the study of rare genetic diseases that involve primary microcephaly, illustrated by the identification of the Microcephalin, abnormal spindle in microcephaly and ataxia-telangiectasia and Rad3-related genes. Furthermore, these findings facilitate the search for the evolutionary changes that have lead to the human brain being so much larger than that of any other primates.
Collapse
Affiliation(s)
- C Geoffrey Woods
- Molecular Medicine Unit, University of Leeds, Clinical Sciences Building, St James's University Hospital, Leeds LS9 7TF, UK.
| |
Collapse
|