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Friday, March 22, 2013

Isochromosomes, Inversions, and a little T21 on top

We're almost to the end of Trisomy Awareness Month and I want to continue sharing the Hope for Trisomy daily tidbits put together by my friend Alisha.

Day 20: Isochromosomes

On our 20th day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share about a rare structural abnormality, known as ISOCHROMOSOME. The chromosomes produced by this abnormal division are one chromosome having the two long arms of the original chromosome, but no short arms, and the other chromosome consisting of the two short arms and no long arms. This constitutes a simultaneous duplication and deletion. Isochromosomes are often found in females with Turner syndrome and can be found in tumors. Share because you Care. ♥

Day 21: Down Syndrome Awareness

On our 21st day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share about the MOST COMMON TRISOMY. Trisomy 21 (Down syndrome) is when there are 3 copies of the chromosome 21, instead of the normal 2. The conditions associated with Down syndrome vary from person to person and can range from mild to severe. However, children with Down syndrome have a widely recognized appearance. Their head may be abnormally shaped and smaller, and the inner corner of the eyes rounded instead of pointed. All Down syndrome individuals experience cognitive delays, but the intellectual disability is usually mild to moderate. This chromosome abnormality occurs in about 1 in 700 newborns. The mother's age is the only factor that has been shown to increase the risk, especially after the mother is 35 years of age. However, since younger women are more likely to have children, the percentage is higher in women younger than 35 years of age. It is important to remember that ALL individuals diagnosed with Down syndrome live happy, productive lives well into adulthood. Share because you Care. ♥

Day 22: Paracentric and Pericentric Inversions

On our 22nd day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share a little more about the STRUCTURAL ABNORMALITY called an INVERSION. An inversion occurs when a chromosome breaks in two places. Then the resulting piece of DNA is reversed and re-inserted into the chromosome. There are 2 types of inversions which are called pericentric and paracentric. The inversion that involves the centromere is called pericentric, and paracentric is when the centromere is not involved. The most common inversion seen in humans in on chromosome 9. This inversion is usually considered harmless, but there are suspicions that it could lead to an increased risk for miscarriage or infertility. An inversion does not mean there is a loss of genetic information, it just simply rearranges it. Share because you Care. ♥

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