Why hemophilia is more rare in females?

Hemophilia being a sex chromosome related recessive disorder has its gene present on X chromosome. Since males have one X and one Y chromosome, and the genes present on X don't have counter genes on Y, only one affected gene(to be present on X) is required for the disease in males. read more

So a female needs to be homozygous to show the phenotype of Haemophilia. See- A female needs to be genotype Xh Xh to be haemophilic. If she is X Xh the dominant gene will supress the recessive one. Hence its rare in females. On the other hand in males its more common because they have only one X chromosome. read more

A female with one affected X chromosome is a “carrier” of hemophilia. Sometimes a female who is a carrier can have symptoms of hemophilia. In addition, she can pass the affected X chromosome with the clotting factor gene mutation on to her children. Learn more about the inheritance pattern for hemophilia. read more

In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, it is very rare for females to have hemophilia. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. read more