There are two different types of hemophilia, Hemophilia A and Hemophilia B. The difference in these two is that they are each located on a different chromosome. Hemophilia A is seven times more common than Hemophilia B.
The hemophilia gene is on the X chromosome. A boy contracts hemophilia when he inherits this chromosome. He gets the hemophilia clotting factors from his mother (Factor Xh).
Father XY Mother (Carrier) XX
Male Baby XhY
Boys (XY) are more likely to have hemophilia because girls (XX) can rely on their other X chromosome if one is mutated. Boys are unable to do this due to the fact that their chromosomes are XY, so they have only one X chromosome.
A boy can even contract hemophilia if his mother is not a carrier. This happens when a gene mutates during its development. Though this is a rare occurrence, 20% of boys with hemophilia contract it this way. This is how the mutated gene enters a family’s bloodline and affects the future generations.
Czar Nicholas III of Russia's son, Prince Alexander, had hemophilia.
"How unfair! Only one health and so many diseases!"
-Victor Schliton
