The karyotype pictured is what happens when there is a full or extra pair for the chromosome 21 and that means the person has Down syndrome. Down syndrome is a genetic defect that causes developmental delays and specific physical characteristics. Some of the physical characteristics are low muscle tone, small body height, upward slanted eyes, and oddly a single deep crease across the center of the palm. Medically 40-50% have congenital heart defects, 65% have hearing issues, and 50% have vision problems. The life expectancy is now 60 years old, but in 1983 it was only 25 years old.
There are three types of Down syndrome. Trisomy 21 (nondisjunction) is the most common form of Down syndrome, which is about 95% of the new cases. It happens where there are three copies of chromosome 21 because there is a pair in the sperm or egg that does not separate. Mosaicism makes up 1% of new cases. This type happens when there is two types of cells, some have the normal 46 and others have 47 the extra one is an extra chromosome 21. People with mosaicism have less traits of Down
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Screening test include blood test and an ultrasound. The quad marker blood test is done during between 15 and 20 weeks pregnant. It looks for issues in the development in the brain and spinal cord in the baby and genetic defects. If done at the right time the test is 69 – 81% accurate. When my mom had this done she was told I had a problem with my spinal cord so they did a special ultrasound and that is when they saw nothing wrong with my spinal cord but they told my mom that I was going to be a big baby. If a problem comes back from the ultrasound then the doctor runs a diagnostic test. The most common is the amniocentesis test which is when they stick a long needle into the uterus to get a sample of the amino fluid to test. There is a risk of miscarriage when this test is