A form of trisomy in which there is an extra copy of chromosome 21 is?

Question

A form of trisomy in which there is an extra copy of chromosome 21 is

Huntingtons disease

Turner syndrome

Duchannes syndrome

Down syndrome

Answer 1

Down's syndrome

Answer 2

Down syndrome, also known as Trisomy 21

Answer 3

Many errors can occur during cell division. In meiosis, the pairs of chromosomes are supposed to split up and go to different spots in the dividing cell; this event is called "disjunction." However, occasionally one pair doesn't divide, and the whole pair goes to one spot. This means that in the resulting cells, one will have 24 chromosomes and the other will have 22 chromosomes. This accident is called "nondisjunction." If a sperm or egg with an abnormal number of chromosomes merges with a normal mate, the resulting fertilized egg will have an abnormal number of chromosomes. In Down syndrome, 95% of all cases are caused by this event: one cell has two 21st chromosomes instead of one, so the resulting fertilized egg has three 21st chromosomes. Hence the scientific name, trisomy 21

Answer 4

Interestingly, Chr 21 and 22 are the only ones in which trisomy is more or less compatible with life. Trisomies of larger chromosomes are spontaneously aborted or die soon after birth. My aunt and uncle gave birth to a daughter with trisomy 18 (edwards syndrome) , it died a few hours after birth due to severe defects.

Answer 5

Down Syndrome

My grandson was born with trisomy 21.

Answer 6

Downs