I need help from a Chromosone genius......?

Question

Ok, i have been told that Down Syndrome is Caused by having a chromosone missing, so does this mean that 2 downs parents will definately have a downs baby, also would it have one or 2 chromosones missing?
Also is it the same choromsone tht is always missing?
I know its a bizzare question, i am a fund raiser and a was speaking to a women whose child was Down's and i was wondering.....

Answer 1

I have 3 yr old boy with Trisomy 21 and have done quite a bit of research on the subject. This is what I've found: Women with Down syndrome can and do have children, but there is a 50 percent chance that their child will have Down syndrome. Men with Down syndrome are believed to be sterile, with only one documented instance of a male with Down syndrome who has fathered a child.

Answer 2

As above, it is an extra chromosome. It is called trisomy 21; Down's Syndrome sufferers have an extra copy of all or part of the twenty first chromosome.
As age increases, the likelihood of having a child with Down's Syndrome increases; at 20 years of age, the chance is almost nil (1/1490); at 49 years of age, the chance is about 8-9% (1/11).

Answer 3

It's an extra 21st chromosome that causes Down's syndrome, not a missing one. People with Down's syndrome have three copies of chromosome 21, instead of the normal two - this is called trisomy 21.

Types of Down's syndrome
There are three types of Down's syndrome:

Regular trisomy 21 - all the cells have an extra chromosome 21. Around 94 per cent of people with Down's syndrome have this type.

Translocation - the extra chromosome 21 material is attached to another chromosome and one of the parent's may carry the translocated chromosome without any signs of the condition themselves. This accounts for around 4 per cent of cases.

Mosaic - only some of the cells have an extra chromosome 21. Around two per cent of people with Down's have this type, which tends to result in milder features.

As to your question, it is highly likely that two Downs parents would produce a Downs baby, although not 100%.

People with Down's syndrome have the right to have personal and sexual relationships, and to get married. The DSA knows of a number of happily married couples where one or both partners have Down's syndrome. It is important that young people with Down's syndrome receive education in the area of relationships and sexuality. As in other areas of learning, they may need more support with this than some of their peers.



Both women and men with Down's syndrome can be fertile, although both sexes have a reduced fertility rate. They therefore need advice on, and access to, contraception. People with Down's syndrome need careful and sensitive advice about having children, as there are a number of issues to consider. Some people with learning disabilities can successfully parent their children, given the right support. However, many couples with learning disabilities decide for themselves not to have children because of the responsibility and hard work involved, or for financial reasons. Where one parent has Down's syndrome, there is a 35% to 50% chance that the child would inherit the syndrome. This chance is even higher where both parents have Down's syndrome. There is also a high chance that pregnancy would end in miscarriage. Women with Down's syndrome are also more likely than other women to have a premature baby, or to need a caesarian section.

Answer 4

Trisomy 21 (Down Syndrome) exists because it is stable enough to produce a viable baby. Other trisomies may result in live births (Trisomy 13, trisomy 18), but the babies die generally within a few days, most are stillborn or result in miscarriages. Other trisomies generally result in miscarriages sometime in the pregnancy. As far as I know, T21 adults are fertile and sexually mature, but if two of them have a child, the resulting embryo may not be genetically stable enough to be viable.

Answer 5

Trisomy 21, that means there is an extra chromosome 21.

The sex cells which are produced by meiosis in these individuals may produce normal gametes which when fuse will produce a zygote.

Since the affected individuals have the extra chromosome in their somatic cells (body), it is not neccesary that when they mate, I'm not completely sure of their fertility that this would be passed on.

Answer 6

down syndrome is caused by a short arm on chromosome #4, but having two downs parents does not mean that the baby will have downs.

Answer 7

as far as i no it an extra chromosome that cause downs syndrome and it has to be d same one all d time as it how the sydrome is recoinised

Answer 8

Nothing missing, they actually have an extra chromosome.

Answer 9

no