Pentasomy X

Pentasomy X

Pentasomy X
File:Foetal karyotype demonstrating pentasomy X.png
Synonyms	49,XXXXX, penta X, XXXXX syndrome<ref name=NIH2018/>
Pronounce
Field
Symptoms	Intellectual disability, short height, low-set ears, decreased muscle tone, developmental delay<ref name=NIH2018/><ref name=NORD2003/>
Complications	Congenital heart disease<ref name=Bee2011/>
Onset
Duration
Types
Causes	5 X chromosomes<ref name=NORD2003/>
Risks	Older parents<ref name=NORD2003/>
Diagnosis	Chromosomal analysis<ref name=NORD2003/>
Differential diagnosis	Down syndrome, triple X syndrome, tetrasomy X, Turner syndrome<ref name=NORD2003/>
Prevention
Treatment	Based on symptoms<ref name=NORD2003/>
Medication
Prognosis
Frequency	Extremely rare<ref name=NORD2003/>
Deaths

Pentasomy X, also known as 49,XXXXX, is a chromosomal abnormality in which a female has five X chromosomes instead of the normal two.<ref name=NORD2003>

Penta X Syndrome(link). NORD (National Organization for Rare Disorders).

2003.

</ref> Signs may include intellectual disability, short height, low-set ears, decreased muscle tone, and developmental delay.<ref name=NIH2018>

49,XXXXX syndrome(link). GARD.

</ref><ref name=NORD2003/> Complications may include congenital heart disease.<ref name=Bee2011>,

 Genetics and Genomics in Nursing and Health Care. online version, 
  
 F.A. Davis, 
  
  
  
 ISBN 9780803629967,</ref>

The condition is due to problems during the formation of the reproductive cells in a person's parents.<ref name=NORD2003/> Risk factors include older parents at the time of conception.<ref name=NORD2003/> Diagnosis is suspected based on symptoms and confirmed by chromosomal analysis.<ref name=NORD2003/>

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/>

Signs and symptoms

The main characteristics of pentasomy X are intellectual disability, short stature and craniofacial abnormalities.<ref name="Cho 2004">Cho, Y. G.,

 A case of 49,XXXXX in which the extra X chromosomes were maternal in origin, 
 Journal of Clinical Pathology, 
 
 Vol. 57(Issue: 9),
 pp. 1004–1006,
 DOI: 10.1136/jcp.2004.017475,
 PMID: 15333671,
 PMC: 1770429,</ref> Other physical traits include the following:

• Small head<ref name="Monheit 1980">Monheit, A.,

 The penta-X syndrome, 
 Journal of Medical Genetics, 
 
 Vol. 17(Issue: 5),
 pp. 392–396,
 DOI: 10.1136/jmg.17.5.392,
 PMID: 7218280,
 PMC: 1048607,</ref>

• Ear abnormalities<ref name="Monheit 1980"/>
• Widely spaced eyes with upward slanting palpebral fissures and epicanthal folds<ref name="Monheit 1980"/>
• Short neck<ref name="Monheit 1980"/>
• Broad nose with a depressed nasal bridge<ref name="Cho 2004"/>
• Hyperextension of the elbows<ref name="Cho 2004"/><ref name="Monheit 1980"/>
• Dental abnormalities and cleft palate<ref name="Cho 2004"/><ref name="Monheit 1980"/>
• Clinodactyly of the fifth finger<ref name="Cho 2004"/><ref name="Monheit 1980"/>
• Deformities of the feet<ref name="Cho 2004"/><ref name="Monheit 1980"/>
• Heart defects<ref name="Monheit 1980"/><ref name="Moraes 2009">Moraes, Lucia M.,

 Detailed analysis of X chromosome inactivation in a 49,XXXXX pentasomy, 
 Molecular Cytogenetics, 
 
 Vol. 2,
 pp. 20,
 DOI: 10.1186/1755-8166-2-20,
 PMID: 19811657,
 PMC: 2766382,</ref>

File:Foetal karyotype demonstrating pentasomy X.png

Foetal karyotype demonstrating pentasomy X

Causes

The aneuploidy is thought to be caused by problems occurring during meiosis, either in the mother or in both the mother and father. Successive nondisjunctions have been observed in the mother of at least one patient.<ref name="Cho 2004"/><ref name="Moraes 2009"/>

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" />

See also

• Trisomy X
• Tetrasomy X

External links

• Tetrasomy & Pentasomy X Syndrome Information and Support

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