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Monday, March 11, 2013

Chromosome Craziness - Centromeres, Structural & Numerical Abnormalities

Be sure to follow Hope for Trisomy on Facebook to get a fun fact all through the month! We are always posting stories, news link, uplifting thoughts... So you'll want to come "like" us!

DAY 8:

On our 8th day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share why the CENTROMERE is so important in the structure of a chromosome. The centromere divides the chromosome into the short and long arms. The centromere is usually not located exactly in the center of the chromosome, and in some cases, is located almost at the chromosome's end. The centromere is important particularly during mitosis (which is the process where a single cell divides resulting in generally two identical cells, each containing the same number of chromosomes and genetic content as that of the original cell). When the centromere is not functioning properly, the chromatids do not align and separate properly, thus, resulting in the wrong number of chromosomes in the daughter cells. This is when we see conditions such as Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), and Patau syndrome (Trisomy 13). Share because you Care. ♥

DAY 9:

On our 9th day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share some history about chromosomes. Did you know that before the chromosomes could be precisely identified they were placed in seven groups? A (chromosomes 1–3), B (chromosomes 4–5), C (chromosomes 6–12 and X), D (chromosomes 13–15), E (chromosomes 16–18), F (chromosomes 19–20), and G (chromosomes 21–22 and Y) ♥ Share because you Care

DAY 10:

On our 10th day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share about chromosome abnormalities. Although there are many types of chromosome abnormalities, they can be organized into two basic groups; NUMERICAL and STRUCTURAL ABNORMALITIES. A NUMERICAL ABNORMALITY is when an individual is missing either a chromosome from a pair (monosomy) or has more than two chromosomes of a pair (trisomy). An example of a condition caused by numerical abnormalities is Down Syndrome, also known as Trisomy 21 (an individual with Down Syndrome has three copies of chromosome 21, rather than two). Turner Syndrome is an example of monosomy, where the individual - in this case a female - is born with only one sex chromosome, an X. A STRUCTURAL ABNORMALITY is when the chromosome's structure is altered, such as in deletions, duplications, translocations, inversions, and rings. Most chromosome abnormalities occur as an accident in the egg or sperm. Therefore, the abnormality is present in every cell of the body. Some abnormalities, however, can happen after conception, resulting in mosaicism, where some cells have the abnormality and some do not. Share because you Care. ♥

DAY 11:

On our 11th day of MARCHING into TRISOMY AWARENESS MONTH, we are going to share a little bit more about NUMERICAL ABNORMALITIES. A numerical abnormality is also referred to as an ANEUPLOIDY (an abnormal number of chromosomes). The 4 common categories of aneuploidy are; Nullisomy, Monosomy, Trisomy, and Tetrasomy. NULLISOMY is when a chromosome is missing altogether. Generally, embryos that are nullisomic don't survive to be born. MONOSOMY is when an individual is missing a chromosome from a pair. TRISOMY is when one extra copy of a chromosome is present. TETRASOMY is when four total copies of a chromosome are present. Tetrasomy is extremely rare. Chromosomal abnormalities, in the form of aneuploidy, are very common among humans. Roughly 8 percent of all conceptions are aneuploid, and it's estimated that up to half of all miscarriages are due to some form of chromosome disorder. Share because you Care. ♥

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