Saturday, January 21, 2012

Trisomy 9

Several months ago I started a series about Trisomy genetic disorders. I'm just getting back to that series after taking a brief break. You may want to refresh your memory on what Trisomy is and how it occurs. I've also written about Trisomy 8.

There are three forms of Trisomy 9:
  1. Full Trisomy 9 is the most severe form in which every cell has three copies of chromosome 9. In most cases the developing embryo is not viable and the pregnancy will end in the first trimester by miscarriage. Some babies with full Trisomy 9 survive until birth, but only live for a short period of time.
  2. Partial Trisomy 9 involves an extra portion of chromosome 9 is included in each cell. You can get an idea of what that might look like here (scroll down to diagnosis). Life expectancy with this form of Trisomy 9 varies widely. This form is generally more rare than full and mosaic forms.
  3. Similar to Trisomy 8, Trisomy 9 often occurs in a mosaic form in which some, but not all, of an individual's cells have three copies of chromosome 9. Depending on the severity of medical challenges the life span of individuals with Mosaic Trisomy 9 can be shortened dramatically.
 Statistically, individuals with Trisomy 9 share several characteristics including medical issues, physical challenges, and behavioral traits. Each affected individual is unique and should not be "expected" to fit a certain developmental profile, but some common challenges include: low birth weight, congenital heart defects, global developmental delays, cognitive challenges, cranio-facial differences, and low muscle tone.
For more information on Trisomy 9, check out the following links:
  • a fairly personal view from one family is here
  • links to several other resources are here
  • a more clinical view
  • break out the tissue for this video about some girl scouts reaching out to one little girl with trisomy 9 mosaic syndrome.


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