Mosaic trisomy 14

What causes mosaic trisomy 14?

Individuals with mosaic trisomy 14 have a duplication of chromosome 14 material in some of their cells, while other cells have a normal chromosomal makeup. The additional chromosomal material is responsible for the features that are characteristic of the condition.

Most cases of mosaic trisomy 14 appear to result from random errors in the separation of chromosomes (nondisjunction) -- either during the division of the egg or sperm in one of the parents, or during cell division after fertilization. There have been some reports in which it may have occurred due to other phenomenon, such as uniparental disomy or the formation of an isochromosome. Uniparental disomy is when an affected individual inherits both copies of a chromosomal pair from one parent, rather than one copy from each parent. An isochromosome is an abnormal chromosome with identical arms on each side of the centromere.

Unique has a leaflet on their Web site that contains additional descriptions and illustrations of how mosaic trisomy 14 may occur. Click here to view the leaflet.

Last updated on 05-01-20

What is mosaic trisomy 14?

Mosaic trisomy 14 is a rare chromosomal disorder in which there are 3 copies (trisomy) of chromosome 14 in some cells of the body, while other cells have the usual two copies. The extent and severity of features in affected individuals can vary. Signs and symptoms that have been most commonly reported include intrauterine growth restriction; failure to to thrive; developmental delay; intellectual disability; distinctive facial characteristics; structural malformations of the heart; and other physical abnormalities. This condition is most often caused by an error in cell division in the egg or sperm cell before conception, or in fetal cells after fertilization. Treatment is directed toward the specific signs and symptoms in each individual.

Last updated on 05-01-20

How might mosaic trisomy 14 be treated?

Treatment for signs and symptoms of mosaic trisomy 14 focuses on the specific features present in each individual. Infants with congenital heart defects may need surgery or other therapies to alleviate symptoms and correct heart malformations. Respiratory infections should be treated aggressively and early. Some infants and children with the condition may need surgical repair of certain craniofacial, genital, or other abnormalities. Early intervention may be important in ensuring that children with the reach their potential. Special services that may be beneficial include special education, physical therapy, and/or other medical, social, and/or vocational services.

Last updated on 05-01-20

Where To Start

Mosiac trisomy 14

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 mosaic trisomy 14.

Last updated on 04-27-20

Name: Chromosome Disorder Outreach CDO PO Box 724
Boca Raton, FL, 33429 , United States
Phone: +1-561-395-4252 Email: Url:
Name: Unique – Rare Chromosome Disorder Support Group G1, The Stables Station Road West
Surrey RH8 9EE
United Kingdom
Phone: +44 (0)1883 723356 Email: Url:
Name: Hope For Trisomy PO Box 121986
Arlington, TX, 76012, United States
Toll Free: 1-866-977-6637 Email: Url:
Name: March of Dimes 1275 Mamaroneck Avenue
White Plains, NY, 10605, United States
Phone: 914-997-4488 Toll Free: 888-663-4637 Fax : 914-997-4763 Email: Url:

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The RareGuru disease database is regularly updated using data generously provided by GARD, the United States Genetic and Rare Disease Information Center.

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