Even though she already has a child with hemophilia, she can still give birth to another. For a mother who carries the hemophilia gene, the chances of giving birth to a child with hemophilia are the same for each pregnancy. It is also possible for all the children in the family to inherit the normal gene or all to inherit the hemophilia gene.įigure 2-3.
The results of one roll do not affect the next roll.Ī family may have children with the hemophilia gene and children without it. Each time a woman is pregnant, her chances of having a child with the hemophilia gene are the same (Figure 2-3). The gene a child will inherit is based purely on chance and can never be truly predicted.Ī child's chances of getting a hemophilia gene do not have anything to do with whether or not brothers or sisters have the gene. But in that group there would be women who had two sons with hemophilia, women who had one with and one without, and women with no sons with hemophilia. In other words, if 500 carriers each had two sons (1,000 total), we would expect there to be about 500 boys with hemophilia. The percentage (%) or "risks" are based on large numbers of births. If a carrier has a daughter, the daughter has a 50% chance of being a carrier.If a carrier has a son, the son has a 50% chance of having hemophilia.All daughters of a man with hemophilia will be carriers (called obligate carriers).No sons of a man with hemophilia will have hemophilia.What are the chances of having a child with hemophilia? It is purely by chance that a hemophilia gene is passed on to produce a child with hemophilia.
It is not the "fault" of one parent since both parents contribute to the outcome.Īll of us have dozens of abnormal genes. However, it is the father's sperm that determines if the child will be a boy or a girl. The mother is the one who passes the hemophilia gene. Does this mean that the mother alone is the one responsible for having a child with hemophilia? She has the gene on one of her X chromosomes and could pass it on to her children. The daughter is called a carrier for hemophilia. It won't allow the instructions from the hemophilia gene to be sent. The daughter will not have hemophilia since the normal blood clotting gene from her mother is dominant. Suppose the X chromosome from her father has the gene for hemophilia. Suppose the X chromosome from her mother has the gene for normal blood clotting. What is a hemophilia carrier?Ī daughter gets an X chromosome from her mother and an X chromosome from her father. This section will explain all of this in more detail. These kinds of defects occur more often in men than in women. Hemophilia is a sex-linked recessivedisorder. If the gene is faulty, the result is hemophiliaunless there is a dominant, normal gene on a matching X chromosome. The gene with the instructions for making factor is found only on the sex chromosome labeled X. How are hemophilia A and B inherited (passed)?
0 kommentar(er)
