Mosaic trisomy 8

What causes mosaic trisomy 8?

Most cases of mosaic trisomy 8 occur due to a random event during the formation of the reproductive cells (egg and sperm) or after fertilization has taken place. An error in cell division (called nondisjunction) may cause some eggs or sperm to have an abnormal number of chromosomes. If an egg or sperm with an extra chromosome 8 contributes to the genetic makeup of an embryo, the embryo will have an extra copy of chromosome 8 in each cell. As the embryo grows and divides, an attempt may be made to correct the mistake by eliminating one extra chromosome 8. In individuals with mosaic trisomy 8, this attempt may be partly successful, leaving some cells with an extra chromosome 8 and some cells with the extra chromosome deleted (the usual chromosome number). This correction process is called trisomy rescue.

In other cases, the egg and sperm may have a normal number of chromosomes, but an error of cell division (nondisjunction) occurs when the fertilized egg is growing and dividing. If an error occurs during one of the divisions, it can cause some cells to have an abnormal number of chromosomes. In people affected by mosaic trisomy 8, some of the body's cells have the usual two copies of chromosome 8, and other cells have three copies of this chromosome (trisomy). The percentage of cells with trisomy 8 and which parts of the body are affected vary from person to person. This leads to variability in the range and severity of symptoms.

Last updated on 05-01-20

Have many cases of mosaic trisomy 8 have been described in the medical literature?

Mosaic trisomy 8 is a rare condition which affects only 1 in every 25,000 to 50,000 liveborn babies. It affects males more often than females. More than 120 people with this condition have been reported in the medical literature.

Last updated on 05-01-20

How might mosaic trisomy 8 be treated?

Because mosaic trisomy 8 affects many different areas of the body, medical management often involves a team of doctors and other healthcare professionals. Treatment for mosaic trisomy 8 varies depending on the signs and symptoms present in each individual. For example, for individuals with delays in motor skills such as walking, physical therapy or occupational therapy may be helpful. Early intervention and special education may be recommended depending on the degree of intellectual disability. If present, cleft palate, cardiac malformations, and kidney malformations may need to be surgically repaired. Other surgeries and interventions may be needed depending on the nature and severity of the other features and their symptoms.

Last updated on 05-01-20

Where To Start

Unique - Mosaic trisomy 8

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 8.

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: Support Organization for Trisomy 18, 13, and Related Disorders (SOFT) c/o Barb Vanherreweghe 2982 South Union Street
Rochester, NY, 14624 , United States
Phone: 585-594-4621 Toll Free: 800-716-SOFT (7638) Email: Url:
Name: Hope For Trisomy PO Box 121986
Arlington, TX, 76012, United States
Toll Free: 1-866-977-6637 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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