Hemophilia is a sex-linked genetic disorder that causes low levels of clotting agents in blood.  There are three different types of hemophilia: Hemophilia A, B, and C.  Hemophilia A is the most common and effects clotting factor 8, while hemophilia B effects clotting factor 9.  This is more common in males because it is a sex-linked trait, meaning that mothers are the carriers of the trait.  Hemophilia C is very rare, and can effect females as well.  The first signs of hemophilia in children include bleeding of the mouth as teeth develop, easy bruising, especially when learning to walk and prolonged nosebleeds.  Blood tests are preformed within the first 1-2 years of life if a child is suspected to have hemophilia, but most adults with mild hemophilia discover it after severe bleeding trauma.