Mosaic Down Syndrome

Mosaic Down Syndrome - Eighty percent die in the first...

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Mosaic Down Syndrome Some of the cells of mosaic Down's sydrome are trisomy 21 but others are normal. This is due to nondisjunction that occurs during mitosis (after fertilization). Mosaic Down Syndrome is likely to be less severe because some of the cells are normal. Trisomy 18 (Edward Syndrome) The incidence of Trisomy 18 is approximately 1 out of every 3000 live births. Trisomy 18 is associated with mental and physical retardation, skull and facial abnormalities, defects in all organ systems, and poor muscle tone. Mean survival is 2 to 4 months. Less than 10% survive to 1 year; a few survive to their 20s or 30s. Trisomy 13 (Patau Syndrome) The incidence of Trisomy 13 is is approximately 1 out of 16,000 live births. Trisomy 13 produces mental and physical retardation, skull and facial abnormalities, and defects in all organ systems. It is also associated with a left lip, a large, triangular nose, and extra digits.
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Unformatted text preview: Eighty percent die in the first month, five to ten percent live past the first year. Polyploidy Polyploidy is a condition in which there is more than 2 sets of chromosomes. Triploids (3N), tetraploids (4N), pentaploids (5N) etc. are polyploids. Polyploidy in Plants Polyploidy is a major evolutionary mechanism in plants. Approximately 47% of all flowering plants are polyploid. Some examples of polyploid plant species are corn, wheat, cotton, sugarcane, apples, bananas, watermelons, and many flowers. Polyploid plants are often more vigorous than the diploid parent species. Polyploid plants are fertile. Polyploidy in Humans Polyploids have defects in nearly all organs. Most die as embryos or fetuses. Occasionally an infant survives for a few days....
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This note was uploaded on 12/15/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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