Can down's syndrome be detected through a pregnant mothers chromosomes via karyotyping rather than amniocentesis?

Answer 1

A normal human male has two 21st chromosomes and a Down syndrome male has three 21st chromosomes.

A human female would have the same karotype with regard to chromosome 21 as a male human.

Answer 2

Karyotyping is a study of the chromosomes to determine any abnormalities that may result in Down syndrome. Karyotyping can be determined with a sample of the amniotic fluid via amniocentesis or chorionic villi sampling (which both pose a threat of miscarriage) or through a blood screening of the mother (which poses no risks or threats to the fetus). Once the samples have been collected, they can then be tested by using a chemical to discontinue mitosis (the creating of new cells) and then kill the cells. Once a dye has been applied, they are then examined, generally with the aid of a computer. If the fetus does have down's syndrome the lab technician will know because there will be three number 21 chromosomes as opposed to two number 21 chromosomes. Amniocentesis is a procedure performed on pregnant women to determine possible risk factors with their developing fetus. A long needle is inserted through the abdomen into the uterus, being guided by an ultrasound, that extracts amniotic fluid. This amniotic fluid is then further tested to determine certain risks such as Down syndrome. Although amniocentesis does have it benefits of obtaining this kind of knowledge, it also poses threats to the fetus such as a .8% chance of miscarriage, clubfeet, trauma to the mother, preterm labor and an infection of the uterus. According to an article published in a Canadian journal, a study in Canada showed that amniocentesis performed between weeks 11 and 13, resulted in 29 out of 4,374 women gave birth to children with clubfeet. Because of this risk, doctors generally try to avoid performing amniocentesis before week 15 of pregnancy. A safer diagnosis of Down syndrome would be through blood screenings. The mother's blood must be drawn then the sample will be sent to a lab for further testing and possible diagnosis. The first screening is generally done between weeks 11 and 13. A second screening is done between week 15 and 20 of the pregnancy. According to the March of Dimes, karyotyping done through prenatal blood screenings cannot diagnose syndrome of the fetus but they can show whether or not the risk is high or low. Although karyoptying is not as accurate as amniocentesis, it is less invasive and poses no harm to the mother or the fetus.

Answer 3

A karyotype is a way of classifying chromosomes. These can be used to diagnose down syndrome because the person will have one too few or one too many chromosomes.