Tetrasomy X

Title

Other Names:

48 XXXX; 48 XXXX syndrome; Tetra X; 48 XXXX; 48 XXXX syndrome; Tetra X; 48,XXXX syndrome; Quadruple X See More

Categories:

Chromosome Disorders; Congenital and Genetic Diseases; Endocrine Diseases; Chromosome Disorders; Congenital and Genetic Diseases; Endocrine Diseases; Female Reproductive Diseases See More

This disease is grouped under:

Numeric sex chromosome variations

Summary Summary

Tetrasomy X is a chromosome disorder that only affects females and is caused by having four copies of the X chromosome instead of two. Females with tetrasomy X have a total of 48 chromosomes in their cells, so this condition is sometimes written as 48, XXXX. The signs and symptoms of tetrasomy X vary, but can include mild to moderate speech and learning difficulties; developmental delay; distinctive facial features; dental abnormalities; hypotonia and joint laxity; radioulnar synostosis; heart defects; hip dysplasia; and problems with ovarian function. An increased risk of childhood infections has also been reported. Tetrasomy X is caused by a random error that occurs during the development of an egg cell and is not caused by anything a mother does during her pregnancy.^[1]^[2]

Last updated: 2/19/2014

Symptoms Symptoms

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms	Other Names	Learn More: HPO ID
30%-79% of people have these symptoms
Abnormality of the dentition	Abnormal dentition Abnormal teeth Dental abnormalities Dental abnormality [ more ]	0000164
Cognitive impairment	Abnormality of cognition Cognitive abnormality Cognitive defects Cognitive deficits Intellectual impairment Mental impairment [ more ]	0100543
Epicanthus	Eye folds Prominent eye folds [ more ]	0000286
Global developmental delay		0001263
Hypertelorism	Wide-set eyes Widely spaced eyes [ more ]	0000316
Joint hyperflexibility	Joints move beyond expected range of motion	0005692
Muscular hypotonia	Low or weak muscle tone	0001252
Radioulnar synostosis	Fused forearm bones	0002974
Specific learning disability		0001328
Strabismus	Cross-eyed Squint Squint eyes [ more ]	0000486
Upslanted palpebral fissure	Upward slanting of the opening between the eyelids	0000582
5%-29% of people have these symptoms
Abnormality of cardiovascular system morphology		0030680
Abnormality of immune system physiology		0010978
Brachydactyly	Short fingers or toes	0001156
Clinodactyly of the 5th finger	Permanent curving of the pinkie finger	0004209
Hip dysplasia		0001385
Premature ovarian insufficiency	Early menopause Premature menopause Premature ovarian failure [ more ]	0008209

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Do you have more information about symptoms of this disease? We want to hear from you.

Last updated: 1/1/2020

Do you have updated information on this disease? We want to hear from you.

Cause Cause

Tetrasomy X is usually caused by a random error in the formation of an egg cell (before pregnancy). In some cases, it may be due to inheriting three X chromosomes from the mother and one X chromosome from the father. In other cases, it may be due to inheriting all four X chromosomes from the mother. During the normal formation of egg cells, each egg cell contains one X chromosome to pass on to offspring. However, errors in cell division can cause an egg cell to have three or four X chromosomes, instead of one. If an egg cell with the extra X chromosomes is fertilized by a sperm cell with one X chromosome, the resulting embryo will have these extra chromosomes. Rarely, tetrasomy X may be caused by an error in cell division that occurs after an egg is fertilized, or by the presence of extra X chromosomes in some of the mother's cells.^[1]

Last updated: 2/19/2014

Organizations Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Association for X and Y Chromosome Variations (AXYS)
P.O. Box 861
Mendenhall, PA 19357
Toll-free: 1-888-999-9428
E-mail: info@genetic.org
Website: https://genetic.org/
Chromosome Disorder Outreach (CDO)
PO Box 724
Boca Raton, FL 33429
Telephone: +1-561-395-4252
E-mail: https://chromodisorder.org/contact/
Website: https://chromodisorder.org/
Unique – Rare Chromosome Disorder Support Group
G1, The Stables
Station Road West
Surrey
RH8 9EE
United Kingdom
Telephone: +44 (0)1883 723356
E-mail: info@rarechromo.org
Website: https://www.rarechromo.org/

Do you know of an organization? We want to hear from you.

Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

Genetics Home Reference (GHR) contains information on Tetrasomy X. This website is maintained by the National Library of Medicine.
Unique is a source of information and support to families and individuals affected by rare chromosome disorders. Click on the link to view information about tetrasomy X.

In-Depth Information

The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
PubMed is a searchable database of medical literature and lists journal articles that discuss Tetrasomy X. Click on the link to view a sample search on this topic.

GARD Answers GARD Answers

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question