Is it possible to have identical twins both with Down Symdrome?

Answer 1

According to scientific studies, only about 90 percent of identical twins with Down's syndrome, will share that disorder with their twin brother or sister.
This is because there are 3 different types of Down syndrome: Standard Trisomy 21, Translocation, and Mosaicism.

Standard Trisomy 21 occurs when the extra chromosome comes from either the egg or the sperm. There is an extra identical copy of the chromosome in each cell. Ninety to ninety-five percent of all cases of Down syndrome are this type. This type is likely to be shared between identical twins.

Translocation occurs when the extra chromosome attaches itself to another chromosome. It does not join the other two number twenty-one chromosomes. The extra genetic material in the cell is the same, leading to the same clinical picture as standard Trisomy 21. This accounts for three to five percent of Down syndrome cases.

Mosaicism occurs when some cells, but not all the cells in the body, contain the extra twenty-first chromosome. As a result, these individuals may exhibit none, some, or all of the characteristics of Down syndrome. This occurs in two to five percent of cases.

Answer 2

Yes, identical means that the egg split AFTER it was fertilized so both halves contain the same exact DNA, including the defect that causes Down Syndrome or any other genetic abnormality.

Answer 3

Yes it is possible. someone i know has an identical twin who has down symdrome.

Answer 4

identical twins are derived from the same fertilized egg due to separation during the blastocyst stage and hence have the same chromosomal composition and hence it follows that both should have Down syndrome because it is a chromosomal defect i.e. trisomy of the chr.21.

Answer 5

Yes. If a zygote with trisomy 21 splits into two embroyos that go on to develop to full term, both infants will have Down Syndrome.

Answer 6

I think that theoretically it is possible especially if the woman is above 40 and taking fertility pills

Answer 7

if they are monozygotic, the yes...because one egg divides into 2 individuals
if they are dizygotic, then it is a possibility, but the odds for 2 eggs to do that are incalculable

Answer 8

If one had down syndrome and the other didn't. They wouldn't be identical, would they?

Answer 9

possible but not guarantied

Answer 10

Yeppers.........