Does this mean that the mother alone is the one responsible for having a child with hemophilia? Third, hemophilia may appear in families with no history of it if the normal blood clotting gene suddenly becomes messed up a spontaneous genetic mutation.
The hemophilia gene seems to appear from nowhere and the family is shocked and confused. The blood clotting gene suddenly becomes faulty. It is purely by chance that a hemophilia gene is passed on to produce a child with hemophilia.
Related Questions. How many brothers were playing in the premiership last year? In most cases, people with an autosomal recessive condition get one gene change from the mother and one gene change from the father. Carrier females have about half the usual amount of coagulation factor VIII or coagulation factor IX, which is generally enough for normal blood clotting.
The two gametes came together during fertilization to produce a diploid individual. Conditions and Diseases. When a gene being examined is present on the X, but not the Y, chromosome, it is X-linked. Hottest Questions.
Females have two X chromosomes in their cells, while males have X and Y chromosomes in their cells. Other genes on the Y chromosome are important for male fertility. A woman who is a carrier has:. No one would have known about the hemophilia gene.
If the baby gets the X chromosome from the father it will be a girl. The clotting factor level will be about the same from one generation to the next.
This means that the presence of a Y chromosome is what causes a fetus to develop as male. For several generations, the women may have had no boy children or by chance had only normal boys. The same goes for men with mild and moderate hemophilia.