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| | {{Short description|A rare chromosomal disorder affecting females}} |
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| == Pentasomy X ==
| | '''Pentasomy X''' is a rare chromosomal disorder that affects females. It is characterized by the presence of three extra X chromosomes, resulting in a total of five X chromosomes (47,XXXXX) instead of the usual two (46,XX). This condition is a form of [[aneuploidy]], which refers to an abnormal number of chromosomes. |
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| {{Infobox medical condition (new)
| | ==Genetics== |
| | name = Pentasomy X
| | Pentasomy X is caused by nondisjunction during [[meiosis]], leading to the presence of three additional X chromosomes. This chromosomal anomaly is not inherited but occurs as a random event during the formation of reproductive cells. The presence of extra X chromosomes affects normal development and function, leading to a variety of clinical features. |
| | synonyms = 49,XXXXX, penta X, XXXXX syndrome<ref name=NIH2018/>
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| | image = Foetal karyotype demonstrating pentasomy X.png
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| | caption =
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| | pronounce =
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| | field =
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| | symptoms = [[Intellectual disability]], short height, [[low-set ears]], [[decreased muscle tone]], [[developmental delay]]<ref name=NIH2018/><ref name=NORD2003/>
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| | complications = [[Congenital heart disease]]<ref name=Bee2011/>
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| | onset =
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| | duration =
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| | types =
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| | causes = 5 [[X chromosomes]]<ref name=NORD2003/>
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| | risks = Older parents<ref name=NORD2003/>
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| | diagnosis = [[Chromosomal analysis]]<ref name=NORD2003/>
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| | differential = [[Down syndrome]], [[triple X syndrome]], [[tetrasomy X]], [[Turner syndrome]]<ref name=NORD2003/>
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| | prevention =
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| | treatment = Based on symptoms<ref name=NORD2003/>
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| | medication =
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| | prognosis =
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| | frequency = Extremely rare<ref name=NORD2003/>
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| | deaths =
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| <!-- Definition and symptoms -->
| | ==Clinical Features== |
| '''Pentasomy X''', also known as '''49,XXXXX''', is a [[chromosomal abnormality]] in which a [[female]] has five [[X chromosome]]s instead of the normal two.<ref name=NORD2003>{{cite web|title=Penta X Syndrome|url=https://rarediseases.org/rare-diseases/penta-x-syndrome/|website=NORD (National Organization for Rare Disorders)|accessdate=22 January 2018|date=2003}}</ref> Signs may include [[intellectual disability]], short height, [[low-set ears]], [[decreased muscle tone]], and [[developmental delay]].<ref name=NIH2018>{{cite web|title=49,XXXXX syndrome|url=https://rarediseases.info.nih.gov/diseases/5678/49xxxxx-syndrome|website=GARD|accessdate=22 January 2018|language=en}}</ref><ref name=NORD2003/> Complications may include [[congenital heart disease]].<ref name=Bee2011>{{cite book|last1=Beery|first1=Theresa A.|last2=Workman|first2=M. Linda|title=Genetics and Genomics in Nursing and Health Care|date=2011|publisher=F.A. Davis|isbn=9780803629967|page=105|url=https://books.google.ca/books?id=WcjZAAAAQBAJ&pg=PA105|language=en}}</ref>
| | Individuals with Pentasomy X may exhibit a range of physical and developmental characteristics. Common features include: |
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| <!-- Cause and diagnosis -->
| | * '''Developmental Delay''': Affected individuals often experience delays in reaching developmental milestones such as sitting, walking, and talking. |
| The condition is due to problems during the formation of the [[reproductive cell]]s in a person's parents.<ref name=NORD2003/> Risk factors include older parents at the time of [[Fertilisation|conception]].<ref name=NORD2003/> Diagnosis is suspected based on symptoms and confirmed by [[chromosomal analysis]].<ref name=NORD2003/>
| | * '''Intellectual Disability''': There is usually some degree of intellectual disability, which can vary from mild to moderate. |
| | * '''Distinctive Facial Features''': These may include a flat nasal bridge, epicanthic folds, and a small jaw (micrognathia). |
| | * '''Skeletal Abnormalities''': Some individuals may have skeletal anomalies such as clinodactyly (curved fingers) or short stature. |
| | * '''Congenital Heart Defects''': Heart defects may be present in some cases. |
| | * '''Hypotonia''': Reduced muscle tone is common, which can affect motor skills. |
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| <!-- Treatment, epidemiology, and history -->
| | ==Diagnosis== |
| Treatment is based on symptoms.<ref name=NORD2003/> The condition is extremely rare, with less than forty reported cases as of 2011.<ref name=NORD2003/><ref name=Bee2011/> The condition was first described in 1963.<ref name=NORD2003/>
| | Pentasomy X is typically diagnosed through [[karyotyping]], a laboratory test that examines the number and structure of chromosomes. Prenatal diagnosis is possible through [[amniocentesis]] or [[chorionic villus sampling]] if there is a suspicion of chromosomal abnormalities. |
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| | ==Management== |
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| | There is no cure for Pentasomy X, and treatment focuses on managing symptoms and supporting development. This may include: |
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| ==Signs and symptoms==
| | * '''Early Intervention''': Programs that provide physical, occupational, and speech therapy can help improve developmental outcomes. |
| The main characteristics of pentasomy X are [[intellectual disability]], short stature and [[craniofacial]] abnormalities.<ref name="Cho 2004">{{Cite journal|last=Cho|first=Y. G.|last2=Kim|first2=D. S.|last3=Lee|first3=H. S.|last4=Cho|first4=S. C.|last5=Choi|first5=S. I.|date=2004-09-01|title=A case of 49,XXXXX in which the extra X chromosomes were maternal in origin|journal=Journal of Clinical Pathology|volume=57|issue=9|pages=1004–1006|doi=10.1136/jcp.2004.017475|issn=0021-9746|pmc=1770429|pmid=15333671}}</ref> Other physical traits include the following:
| | * '''Educational Support''': Special education services tailored to the individual's needs can aid in learning and skill development. |
| | * '''Medical Monitoring''': Regular check-ups with healthcare providers to monitor growth, development, and any associated health issues. |
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| * [[Microcephaly|Small head]]<ref name="Monheit 1980">{{Cite journal|last=Monheit|first=A.|last2=Francke|first2=U.|last3=Saunders|first3=B.|last4=Jones|first4=K. L.|date=1980-10-01|title=The penta-X syndrome|journal=Journal of Medical Genetics|volume=17|issue=5|pages=392–396|issn=0022-2593|pmc=1048607|pmid=7218280|doi=10.1136/jmg.17.5.392}}</ref>
| | ==Prognosis== |
| * Ear abnormalities<ref name="Monheit 1980"/>
| | The prognosis for individuals with Pentasomy X varies depending on the severity of symptoms and the presence of associated health conditions. With appropriate support and interventions, many individuals can lead fulfilling lives. |
| * [[hypertelorism|Widely spaced eyes]] with upward slanting [[palpebral fissures]] and [[epicanthal folds]]<ref name="Monheit 1980"/>
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| * Short neck<ref name="Monheit 1980"/>
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| * Broad nose with a depressed [[nasal bridge]]<ref name="Cho 2004"/>
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| * Hyperextension of the elbows<ref name="Cho 2004"/><ref name="Monheit 1980"/>
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| * Dental abnormalities and [[cleft palate]]<ref name="Cho 2004"/><ref name="Monheit 1980"/>
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| * [[Clinodactyly]] of the fifth finger<ref name="Cho 2004"/><ref name="Monheit 1980"/>
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| * Deformities of the feet<ref name="Cho 2004"/><ref name="Monheit 1980"/>
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| * [[Heart defect]]s<ref name="Monheit 1980"/><ref name="Moraes 2009">{{Cite journal|last=Moraes|first=Lucia M.|last2=Cardoso|first2=Leila Ca|last3=Moura|first3=Vera Ls|last4=Moreira|first4=Miguel Am|last5=Menezes|first5=Albert N.|last6=Llerena|first6=Juan C.|last7=Seuánez|first7=Héctor N.|date=2009-10-07|title=Detailed analysis of X chromosome inactivation in a 49,XXXXX pentasomy|journal=Molecular Cytogenetics|volume=2|pages=20|doi=10.1186/1755-8166-2-20|issn=1755-8166|pmc=2766382|pmid=19811657}}</ref>
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| [[File:Foetal karyotype demonstrating pentasomy X.png|thumb|500px|Foetal karyotype demonstrating pentasomy X]]
| | ==Related Pages== |
| | | * [[Aneuploidy]] |
| ==Causes== | | * [[Karyotype]] |
| The [[aneuploidy]] is thought to be caused by problems occurring during [[meiosis]], either in the mother or in both the mother and father. Successive [[nondisjunction]]s have been observed in the mother of at least one patient.<ref name="Cho 2004"/><ref name="Moraes 2009"/>
| | * [[Chromosomal disorder]] |
| | | * [[Intellectual disability]] |
| The features of the syndrome likely arise due to failure of [[X-inactivation]] and the presence of multiple X chromosomes from the same parent causing problems with [[parental imprinting]]. In theory, X-inactivation should occur and leave only one X chromosome active in each cell. However, failure of this process has been observed in one individual studied. The reason for this is thought to be the presence of an unusually large, and imbalanced, number of X chromosomes interfering with the process.<ref name="Moraes 2009" />
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| ==See also==
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| * [[Trisomy X]] | |
| * [[Tetrasomy X]] | |
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| ==References==
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| {{Reflist}}
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| == External links ==
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| {{Medical resources
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| | ICD10 = Q97.1
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| | ICD9 = <!--{{ICD9|xxx}}-->
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| | MeSH = C535319
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| | Orphanet = 11
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| }}
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| *[http://www.genealogysource.com/tetra_x Tetrasomy & Pentasomy X Syndrome Information and Support]
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| {{Chromosomal abnormalities}}
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| | [[Category:Genetic disorders]] |
| | [[Category:Chromosomal abnormalities]] |
| [[Category:Rare diseases]] | | [[Category:Rare diseases]] |
| [[Category:Sex chromosome aneuploidies]]
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| [[Category:RTT]]
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| {{stub}}
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A rare chromosomal disorder affecting females
Pentasomy X is a rare chromosomal disorder that affects females. It is characterized by the presence of three extra X chromosomes, resulting in a total of five X chromosomes (47,XXXXX) instead of the usual two (46,XX). This condition is a form of aneuploidy, which refers to an abnormal number of chromosomes.
Genetics
Pentasomy X is caused by nondisjunction during meiosis, leading to the presence of three additional X chromosomes. This chromosomal anomaly is not inherited but occurs as a random event during the formation of reproductive cells. The presence of extra X chromosomes affects normal development and function, leading to a variety of clinical features.
Clinical Features
Individuals with Pentasomy X may exhibit a range of physical and developmental characteristics. Common features include:
- Developmental Delay: Affected individuals often experience delays in reaching developmental milestones such as sitting, walking, and talking.
- Intellectual Disability: There is usually some degree of intellectual disability, which can vary from mild to moderate.
- Distinctive Facial Features: These may include a flat nasal bridge, epicanthic folds, and a small jaw (micrognathia).
- Skeletal Abnormalities: Some individuals may have skeletal anomalies such as clinodactyly (curved fingers) or short stature.
- Congenital Heart Defects: Heart defects may be present in some cases.
- Hypotonia: Reduced muscle tone is common, which can affect motor skills.
Diagnosis
Pentasomy X is typically diagnosed through karyotyping, a laboratory test that examines the number and structure of chromosomes. Prenatal diagnosis is possible through amniocentesis or chorionic villus sampling if there is a suspicion of chromosomal abnormalities.
Management
There is no cure for Pentasomy X, and treatment focuses on managing symptoms and supporting development. This may include:
- Early Intervention: Programs that provide physical, occupational, and speech therapy can help improve developmental outcomes.
- Educational Support: Special education services tailored to the individual's needs can aid in learning and skill development.
- Medical Monitoring: Regular check-ups with healthcare providers to monitor growth, development, and any associated health issues.
Prognosis
The prognosis for individuals with Pentasomy X varies depending on the severity of symptoms and the presence of associated health conditions. With appropriate support and interventions, many individuals can lead fulfilling lives.
Related Pages
