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Good luck in your quest and thank you for following us. There are two types of haplogroups: mtDNA Haplogroup : Both men and women have mtDNA, or mitochondrial DNA, in their bodies, but it is only passed down by mothers to their daughters , in a direct female line of descent.
It passes its variations on from father to son only, in a direct male line of descent. As a result, only men can follow their paternal lineage. You inherited your mitochondrial DNA from your mother, who inherited hers from her mother and so forth. Large structures called autophagosomes, for instance, are known to engulf paternal mitochondria shortly after a sperm penetrates an egg.
Xue and his colleagues found, however, that the paternal mitochondria in the roundworms actually started to break down before any autophagosomes reached them. The researchers identified a gene, called cps-6, that seemed to initiate the breakdown process within paternal mitochondria.
They found that deleting cps-6 caused paternal mitochondria to linger longer in the embryo. It also led to higher rates of embryonic death. Margarida Azevedo, MSc. She worked as a molecular biologist research associate at a Cambridge UK-based biotech company that discovers and develops therapeutic, fully human monoclonal antibodies. Print This Page. How useful was this post? Click on a star to rate it! As you found this post useful Follow us on social media!
In about half of all miscarriages occuring in the first 3 months of pregnancy, the developing baby has an altered number of chromosomes. Will gene therapy make a difference? As we understand more about how the genes on chromosome 21 interact to cause Down's syndrome, we can imagine a situation in which it might eventually become possible to switch off some of the genes or maybe even the whole extra chromosome responsible for Down's syndrome.
A great deal more understanding of the basic mechanisms of Down's syndrome and a great deal more development in gene therapy is needed before we can contemplate such treatment, but it remains a long-term possibility. Are there any differences in the genes or chromosomes of grandparents of children with Down's syndrome?
Unless the grandparent is a carrier of a balanced translocation a very rare event there are no known differences in the genes or chromosomes of grandparents of children with Down's syndrome from those of anyone else's grandparents. There is nothing known that the grandparents might have done which would explain their grandchild being born with Down's syndrome.
Can adults with Down's syndrome have children; and if so, what is the chance of their children having the condition?
A woman with Down's syndrome can have children. There have been only a few reports of men with Down's syndrome fathering children. If both partners have Down's syndrome there is a high chance of their children having the condition. As these events are still rare it is difficult to obtain accurate figures. My grandmother's sister had Down's syndrome. She died 40 years ago when she was Does this mean that I could have an increased chance of having a baby with the condition?
It is unlikely. There is a small chance that she would have had the inherited form of translocation Down's syndrome, in which case you could be a carrier. Chromosome testing was not introduced until so the family may not know what kind of Down's syndrome she had.
If your grandmother had a lot of children and grandchildren and none of them was affected, it is very unlikely that she was a carrier. If you want to be completely sure that you are not a carrier, chromosome test would need to be carried out on your blood.
People with Down's syndrome are all very different from each other, in looks and personality and ability. Why is this, when they all have extra material from chromosome 21?
People with Down's syndrome get the extra chromosome material along with the full set of chromosomes from their parents. All the genes they inherit are ordinary ones, which explains why they resemble their families in the same way as ordinary children.
The differences in genes that children with Down's syndrome inherit from their parents, together with differences in their environment, explain the differences between one child with Down's syndrome and another. Can the tests ever be wrong?
If an experienced health professional has seen features of Down's syndrome in your child, and the blood test result shows regular trisomy 21 or a translocation type, there should be no doubt. In mosaic Down's syndrome, because all the cells in the body do not show trisomy, it is possible for a blood sample not to include any trisomic cells, or to contain only trisomic cells, which may lead to difficulties in arriving at the correct diagnosis.
In this situation, while further tests may help, it is not actually possible to disprove mosaicism. Blood tests are done by humans. Mistakes can, of course, be made at one of the many stages that a blood sample passes through before a result is given to the patient. This, however, is very rare. Cuckle, N. Wald and S. Thompson British Journal of Obstetrics and Gynaecology, vol. Alberman et al.
Souvenir Press. Selikowitz Down Syndrome: The Facts. Oxford University Press. The Genetics of Down's Syndrome This article explains what is known about the genetics of Down's syndrome. Genes therefore control or influence such things as: Our physical appearance The way babies and children grow and develop, even before they are born The timing of the milestones of growth and development The body's supply and use of building and maintenance materials The way the body ages A person's resistance to illness Genes are passed from parents to children.
There are three main types of Down's syndrome: Regular trisomy 21 - also known as standard or free trisomy 21 - in which all the cells have an extra chromosome Translocation - in which extra chromosome 21 material is attached to another chromosome. Mosaic - in which only some of the cells have an extra chromosome Regular Trisomy 21 Most people with Down's syndrome have this type. The chromosomes that can be involved are numbers 13, 14, 15, 21, Because it is a new event, this is sometimes called a de novo translocation.
Genetic counselling should always be available to families with a child with Down's syndrome. Summary Down's syndrome is always caused by the presence of extra chromosome 21 material in a person's cells.
There are 3 types of Down's syndrome. Most people with the condition have regular trisomy Much smaller numbers have translocation, or mosaic Down's syndrome. The only way of finding out what type of Down's syndrome people have is to do a blood test and examine their chromosomes under a microscope. One of their parents will be a carrier of the translocation. These parents have an increased chance of having a second child with the condition.
There is no known reason why Down's syndrome occurs except on the rare occasions when it has been inherited.
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