Turner syndrome: the case of the missing sex chromosome

ABSTRACT:Regional cerebral glucose metabolism was examined in females with Turner syndrome, a sex chromosome abnormality. Previous studies have found a visual/spatial cognitive anomaly in these women but, to date, no abnormalities in brain structure or function have been associated with the condition. In the present study, decreases in regional metabolism were found in the occipital and parietal cortex. The involvement of the occipital cortex, although consistent with the observed cognitive anomalies, has not been suggested previously as an area dysfunction. Because the occipital cortex is a primary sensory cortex, the reduction of glucose metabolism in the parietal cortex may reflect a lack of innervation from the occipital cortex. Besides insight into the functional specialization of the brain, these findings are also consistent with previous reports on animals regarding the effects of estrogen in brain maturation.

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The Hypothesis of the Prolonged Cell Cycle in Turner Syndrome

10.20944/preprints202101.0098.v1 ◽

2021 ◽

Author(s):

Francisco Álvarez-Nava

Keyword(s):

Cell Cycle ◽

Turner Syndrome ◽

Low Birthweight ◽

Sex Chromosome ◽

Heart Diseases ◽

Cellular Growth ◽

Proliferating Cells ◽

Cycle Frequency ◽

Increased Risk ◽

New Findings

Turner syndrome (TS) is a chromosomal disorder that is caused by a missing or structurally abnormal second sex chromosome. Subjects with TS are at an increased risk of developing intrauterine growth retardation, low birthweight, short stature, congenital heart diseases, infertility, obesity, dyslipidemia, hypertension, insulin resistance, type 2 diabetes mellitus, metabolic syndrome, and cardiovascular diseases (stroke and myocardial infarction). The underlying pathogenetic mechanism of TS is unknown. The assumption that X chromosome-linked gene haploinsufficiency is associated with the TS phenotype is questioned since such genes have not been identified. Thus, other pathogenic mechanisms have been suggested to explain this phenotype. Morphogenesis encompasses a series of events that includes cell division, the production of migratory precursors and their progeny, differentiation, programmed cell death and integration into organs and systems. The precise control of the growth and differentiation of cells is essential for normal development. The cell cycle frequency and the number of proliferating cells are essential in cell growth. 45,X cells have a failure to proliferate at a normal rate, leading to a decreased cell number in a given tissue during organogenesis. A convergence of data indicates an association between a prolonged cell cycle and the phenotypical features in Turner syndrome. This review aims to examine old and new findings concerning the relationship between a prolonged cell cycle and TS phenotype. These studies reveal a diversity of phenotypic features in TS that could be explained by reduced cell proliferation. The implications of this hypothesis for our understanding of the TS phenotype and its pathogenesis are discussed. It is not surprising that 45,X monosomy leads to cellular growth pathway dysregulation with profound deleterious effects on both embryonic and later stages of development. The prolonged cell cycle could represent the beginning of the pathogenesis of TS, leading to a series of phenotypic consequences in embryonic/fetal, neonatal, pediatric, adolescence, and adulthood life.

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Concurrent Van der Woude syndrome and Turner syndrome: A case report

SAGE Open Medical Case Reports ◽

10.1177/2050313x16687916 ◽

2017 ◽

Vol 5 ◽

pp. 2050313X1668791 ◽

Cited By ~ 2

Author(s):

Evan Los ◽

Hayley Baines ◽

Ines Guttmann-Bauman

Keyword(s):

Short Stature ◽

Turner Syndrome ◽

Sex Chromosome ◽

Delayed Diagnosis ◽

Chromosome 1 ◽

Pituitary Insufficiency ◽

Van Der Woude Syndrome ◽

Unique Case ◽

Second Sex ◽

Interferon Regulatory Factor 6

Most cases of Van der Woude syndrome are caused by a mutation to interferon regulatory factor 6 on chromosome 1. Turner syndrome is caused by complete or partial absence of the second sex chromosome in girls. We describe a unique case of the two syndromes occurring concurrently though apparently independently in a girl with Van der Woude syndrome diagnosed at birth and Turner syndrome at 14 years 9 months. Short stature was initially misattributed to Van der Woude syndrome and pituitary insufficiency associated with clefts before correctly diagnosing Turner syndrome. We discuss the prevalence of delayed diagnosis of Turner syndrome, the rarity of reports of concurrent autosomal chromosome mutation and sex chromosome deletion, as well as the need to consider the diagnosis of Turner syndrome in all girls with short stature regardless of prior medical history.

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Testing for sex chromosome mosaicism in Turner syndrome

International Congress Series ◽

10.1016/j.ics.2006.06.002 ◽

2006 ◽

Vol 1298 ◽

pp. 9-12

Author(s):

Daniel L. Van Dyke ◽

Anne E. Wiktor

Keyword(s):

Turner Syndrome ◽

Sex Chromosome ◽

Chromosome Mosaicism

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Protocol: New approaches to managing the social deficits of Turner Syndrome using the PEERS program

F1000Research ◽

10.12688/f1000research.15489.1 ◽

2018 ◽

Vol 7 ◽

pp. 1864

Author(s):

Jeanne Wolstencroft ◽

William Mandy ◽

David Skuse

Keyword(s):

Social Skills ◽

Turner Syndrome ◽

Sex Chromosome ◽

Controlled Trial ◽

Clinical Care ◽

Case Series ◽

Autism Spectrum ◽

Autism Spectrum Conditions ◽

Small Scale ◽

Intervention Programme

Turner Syndrome (TS) is a sex chromosome aneuploidy (45,X) associated with social skill difficulties. Recent clinical care guidelines recommend that the Program for the Education and Enrichment of Relational Skills (PEERS) social skills intervention programme be trialled in this population. PEERS has been successfully used in adolescents with autism spectrum conditions without intellectual disabilities. The PEERS program will be piloted with adolescents and young women with TS aged 16-20 using an uncontrolled study trial with a multiple-case series design. The program will be delivered face to face and online. The assessment battery is designed to measure social skills comprehensively from diverse informants (parent, teacher young person). It includes measures of social performance, social knowledge and social cognition. Parents and young people taking part in the intervention will also feedback on the acceptability and feasibility of the pilot. The outcomes of this small scale pilot (n=6-10) will be used to adapt the programme based on feedback and estimate the sample for a future randomised controlled trial.

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Craniofacial growth and development of Turner syndrome children

Padjadjaran Journal of Dentistry ◽

10.24198/pjd.vol21no2.14104 ◽

2009 ◽

Vol 21 (2) ◽

Author(s):

Inne Suherna Sasmita ◽

Arlette Suzy Puspa Pertiwi ◽

M Harun Achmad

Keyword(s):

Turner Syndrome ◽

Growth And Development ◽

Sex Chromosome ◽

Genetic Disorder ◽

Chromosome Constitution ◽

Whole Body ◽

Craniofacial Growth ◽

Oral Manifestations ◽

Permanent Molars ◽

First Permanent Molars

Turner syndrome is a genetic disorder which characterized by specific physical appearance and the lost of one of sex chromosome in females. The most frequent chromosome constitution in Turner syndrome is 45X. This disorder may cause an interruption of growth and development in the whole body as well as in the craniofacial region. The oral manifestations of Turner syndrome are micrognathia, high palate, malocclusion, and the premature eruption of first permanent molars. This paper will discuss the oral manifestations associated with the craniofacial growth and development of Turner syndrome.

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A Rare Variant of Turner Syndrome (the X Isochromosome-X Syndrome): A Case Report

Disease and Diagnosis ◽

10.34172/ddj.2021.31 ◽

2021 ◽

Vol 10 (4) ◽

pp. 177-179

Author(s):

Hamid Reza Samimagham ◽

Mitra Kazemi Jahromi

Keyword(s):

Turner Syndrome ◽

Rare Variant ◽

Rare Variants ◽

Sex Chromosome ◽

Clinical Manifestations ◽

Chromosome Anomaly ◽

Primary Amenorrhea ◽

Hypergonadotropic Hypogonadism ◽

Case Presentation ◽

Genetic Problem

Background: Turner syndrome occurs in nearly one in every 2000-5000 female births. This syndrome is a genetic problem in the female phenotype and the most common sex chromosome anomaly. It is diagnosed based on clinical manifestations and cytogenetic examinations. The classic syndrome (i.e., monosomy X) makes up 50% of the cases while other forms contain X chromosome variants, which do not typically manifest as the classic X phenotype. Case Presentation: This study, presents a rare variant of Turner syndrome reported in a 20-year-old woman presenting with primary amenorrhea, hypothyroidism, and short stature who had hypergonadotropic hypogonadism with hypoplastic ovaries while without the clinical manifestations of the classic Turner syndrome. The karyotype was determined as X isochromosome-X syndrome [46 XXi (Xq)]. Conclusion: This rare syndrome occurs in approximately 7% of the cases of Turner syndrome. Rare variants of the syndrome should also be considered in female patients without the classic manifestations of Turner syndrome.

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Sex Chromosome Variations: Turner Syndrome

Intersex ◽

10.4324/9781003103554-13 ◽

2020 ◽

pp. 171-175

Author(s):

Catherine Harper

Keyword(s):

Turner Syndrome ◽

Sex Chromosome

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Health Supervision for Children With Turner Syndrome

PEDIATRICS ◽

10.1542/peds.96.6.1166 ◽

1995 ◽

Vol 96 (6) ◽

pp. 1166-1173

Author(s):

Keyword(s):

Short Stature ◽

Turner Syndrome ◽

X Chromosome ◽

Sex Chromosome ◽

First Trimester ◽

Clinical Findings ◽

Chromosome Constitution ◽

Birth Prevalence ◽

Frequent Use ◽

Wide Range

This set of guidelines is designed to assist the pediatrician in caring for the child in whom the diagnosis of Turner syndrome has been confirmed by karyotype. Although the pediatrician's first contact with the child is usually during infancy, occasionally the pregnant woman who has been given the prenatal diagnosis of Turner syndrome will be referred for advice. Therefore, these guidelines offer advice for this situation as well. Turner syndrome, as used here, refers to a condition in which there is short stature and ovarian dysgenesis in females because of the absence of a normal second sex chromosome. Nonchrornosomal gonadal dysgenesis is excluded. The birth prevalence of Turner syndrome has been estimated to be from 1:2000 to 1:5000 female live births. About 1% to 2% of all conceptuses have a 45,X chromosome constitution. Of these, the majority (99%) spontaneously abort, usually during the first trimester of pregnancy. With the more frequent use of ultrasound, it is recognized that some pregnancies with a fetal 45,X chromosome constitution progressing into the second trimester are associated with nuchal cysts, severe lymphedema, or hydrops fetalis. These pregnancies are associated with a high frequency of fetal death. PHENOTYPE Pediatricians are most familiar with the clinical findings that prompt the diagnosis in children, namely, short stature and the classic Turner syndrome features such as lymphederna, webbed neck, low posterior hair line, and cubitus valgus. A wide range of clinical abnormalities may be found (Table 1). Turner syndrome, however, is not always accompanied by distinctive features and most often is not diagnosed in infancy.

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Cognitive and Behavioral Manifestations in Turner Syndrome

Cognitive and Behavioral Abnormalities of Pediatric Diseases ◽

10.1093/oso/9780195342680.003.0029 ◽

2010 ◽

Author(s):

Aysenil Belger ◽

Sarah J. Hart

Keyword(s):

Turner Syndrome ◽

Health Care Providers ◽

X Chromosome ◽

Behavioral Problems ◽

Structural Changes ◽

Sex Chromosome ◽

Genetic Disorder ◽

Clinical Manifestations ◽

Expression Of Genes ◽

Recessive Genes

Turner Syndrome (TS) is a common genetic disorder that affects approximately 1 in 1,900 live female births. Like other sex chromosome abnormalities (SCAs), TS has high morbidity due to associated congenital abnormalities, neurodevelopmental disturbances, neurocognitive deficits, and social-behavioral problems. Many individuals with TS are not diagnosed. Those who are identified may be subject to inadequate care, bias, and discrimination because of a poor understanding of the condition among families, health care providers, and educators, especially regarding developmental profiles and outcomes. Turner syndrome results from an abnormal or missing second sex (i.e., X) chromosome, and by definition, affects only females. There is tremendous variability in the clinical presentations of individuals with TS that is likely due to the variable nature of the genetic abnormality. Approximately 50% of girls with TS have a 45X karyotype (Savendahl and Davenport 2000; Soriano-Guillen et al. 2005; Sybert and McCauley 2004), with the remainder having either a structural abnormality or mosaicism involving the X chromosome. Structural changes of the X chromosome include deletions, breakage of both arms to form a ring chromosome, or breakage and exchange in the X centromere region to form an isochromosome. Common mosaic patterns include 45,X/46,XX, 45,X/46,X,i(X), and 45, X/46,XY (Table 19.1). Correlations of clinical phenotype with cytogenetic data are further complicated by the wide range of structural abnormalities, as well as by mosaicism, differences in X-inactivation patterns, and the presence of abnormal recessive genes (Ogata and Matsuo 1995). Girls with 45X karyotype tend to be most severely affected, and there is less variability within this group than in the population as a whole. Many of the clinical manifestations of TS can be understood in the context of reduced expression of genes on the X chromosome (Neely 1994; Zinn and Ross 1998; Zinn et al. 1998). In normal females, one X chromosome is inactivated; however, the process is not complete. Genes on the X-chromosome that are not inactivated, so-called pseudoautosomal genes, are present in a cluster near the tip of the short arm and scattered elsewhere.

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