HAEMOPHILIA

 Haemophilia: Haemophilia is a genetical disease. Expression of this disease occurs in Male while female remain as carrier. This is because human being has one pair of sex chromosome and in that pair it may comprise XY  or XX chromosome and if it is XY then it is Male in Humans and if it is XX then it is Female in Humans. Haemophilia is a sex linked recessive disease. It is due to the recessive gene on X chromosome. In case of human female there is the occurrence of two X chromosome, so if in one of the X chromosome the gene for haemophilia is there, than in female there is the occurrence of another X which gives its expression. But in case of Male there is the occurrence of one X chromosome and if that X chromosome has the gene for Haemophilia than the expression of Haemophilia occurs in the male. Therefore, females are carrier and if males have the gene then they are infected and diseased. 

In this disease , a single protein that is part of the cascade of proteins involved in the clotting of blood is affected. Due to this, if there is a minor cut then blood keep on coming out. The disease is therefore transmitted to a son from a carrier mother. It is also known by another name as Bleeding disease or Royal Disease. Royal Disease named because males of Queen Victoria in different generations suffered from this disease.