Trisomy X

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Introduction

Trisomy X is a caused by the presence of an extra X chromosome in females (47,XXX instead of 46,XX). This is also the most common female chromosomal abnormality, occurring in approximately 1 in 1,000 female births.

Other abnormalities of chromosome number include: female tetrasomy X (quadruple X, or 48, XXXX) a rare chromosomal disorder and male Klinefelter syndrome, the presence of an additional X chromosome (47, XXY or XXY).

Alternative names: Triplo X syndrome, Trisomy X, 47,XXX, XXX syndrome

Genetic Links: Introduction | Genetic risk maternal age | Trisomy 21 | Trisomy 18 | Trisomy X | Fragile X | Williams | Philadelphia chromosome | Prenatal Diagnosis | Neonatal Diagnosis | International Classification of Diseases | Molecular Development - Genetics| Genital System - Abnormalities

Some Recent Findings

A review of trisomy X (47,XXX) "Trisomy X is a sex chromosome anomaly with a variable phenotype caused by the presence of an extra X chromosome in females (47,XXX instead of 46,XX). It is the most common female chromosomal abnormality, occurring in approximately 1 in 1,000 female births." Root length in the permanent teeth of women with an additional X chromosome (47,XXX females) "Increased enamel thickness in the teeth of 47,XXX females is apparently caused by the active enamel gene in all X chromosomes having no increased influence on crown dentin formation. These results in 47,XXX females indicate an increase in root dentin development, at least in the mandible, which together with the data on crown formation reflects a continuous long-lasting effect of the X chromosome on dental development."

Prenatal Diagnosis

The most common prenatal diagnosis is by either amniocentesis or chorionic villi sampling.

Links:Amniocentesis | Chorionic villus sampling

Physical Features

Feature	Estimated frequency based on current available data
Tall stature >75th percentile	80 - 89 %
Epicanthal folds	32 - 46 %
Clinodactyly	42 - 65 %
Hypotonia in infancy	55 - 71 %
Genitourinary malformations	5 - 16 %
Seizure disorder	11 - 15 %
Intention tremor	6 - 20 %
Congenital hip dysplasia	2 - 12 %
Constipation/Abdominal pains	12 - 45 %
Premature ovarian failure	unknown

Table data from Tartaglia NR, etal., 2010

References

Reviews

Nicole R Tartaglia, Susan Howell, Ashley Sutherland, Rebecca Wilson, Lennie Wilson A review of trisomy X (47,XXX). Orphanet J Rare Dis: 2010, 5();8 PMID:20459843

Jeannie Visootsak, John M Graham Klinefelter syndrome and other sex chromosomal aneuploidies. Orphanet J Rare Dis: 2006, 1();42 PMID:17062147

Articles

Aniel Jessica Leticia Brambila-Tapia, Horacio Rivera, Herbert García-Castillo, Maria Guadalupe Domínguez-Quezada, Ingrid Patricia Dávalos-Rodríguez 47,XXX/45,X/46,XX mosaicism in a patient with Turner phenotype and spontaneous puberal development. Fertil. Steril.: 2009, 92(5);1747.e5-7 PMID:19732877

T Lester, M de Alwis, P A Clark, A M Jones, F Katz, R J Levinsky, C Kinnon Trisomy X in a female member of a family with X linked severe combined immunodeficiency: implications for carrier diagnosis. J. Med. Genet.: 1994, 31(9);717-20 PMID:7815443

K Tennes, M Puck, K Bryant, W Frankenburg, A Robinson A developmental study of girls with trisomy X. Am. J. Hum. Genet.: 1975, 27(1);71-80 PMID:1155452

A W JOHNSTON, M A FERGUSON-SMITH, S D HANDMAKER, H W JONES, G S JONES The triple-X syndrome. Clinical, pathological, and chromosomal studies in three mentally retarded cases. Br Med J: 1961, 2(5259);1046-52 PMID:14452136

Search PubMed

Search Pubmed: Trisomy X

External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name.

• Genetics Home Reference triple X syndrome

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Dr Mark Hill 2013, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G