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Diseases

Genetic and Rare Diseases Information Center (GARD)

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Mosaic trisomy 8


Other Names for this Disease
  • Mosaic trisomy chromosome 8
  • Trisomy 8 mosaicism
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Overview



What is mosaic trisomy 8?   

What are the signs and symptoms of mosaic trisomy 8?


What is mosaic trisomy 8?   

Mosaic trisomy 8 is a chromosome disorder defined by the presence of three copies of chromosome 8 in some cells of the body. It is characterized by distinctive facial features; mild intellectual disability; and joint, kidney, cardiac, and skeletal abnormalities. Males are more frequently affected than females. In the absence of serious problems, life expectancy is normal. Complete trisomy 8 is lethal and often results in miscarriage during the first trimester. Mosaic trisomy 8 is the result of a random error in the egg or sperm. Diagnosis is based on karyotype analysis. Mosaic trisomy 8 almost always occurs in individuals with no family history of the condition.[1] 
Last updated: 7/25/2011

What are the signs and symptoms of mosaic trisomy 8?

The facial features are usually mild and can include elongation of the skull (scaphocephaly), prominent forehead, widely-spaced eyes, deeply set eyes, broad upturned nose, micrognathia, and ear abnormalities. Additional features can include: agenesis of the corpus callosum, highly arched or cleft palate, short and large neck, high stature, elongated thin trunk, and narrow shoulders and pelvis. Kidney and cardiac abnormalities are frequent. Camptodactyly, stiff joints, absent malformed kneecap, vertebral malformations such as scoliosis, as well as eye abnormalities also commonly observed.[1]

Most affected individuals have moderate intellectual disabilities (IQ between 50 and 75), with some people having a normal intelligence. There is no correlation between the percentage of trisomic cells and the severity of the intellectual deficit. Mosaic trisomy 8 also seems to predispose to Wilms tumors, myelodysplasias, and myeloid leukemia.[1]
Last updated: 7/25/2011

References
  1. Verloes A. Mosaic trisomy 8. Orphanet. April 2009; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=96061. Accessed 7/25/2011.