Haemophilia (Paperback)

High Quality Content by WIKIPEDIA articles Haemophilia (also spelled hemophilia in North America, from the Greek haima 'blood' and philia 'love') is a group of hereditary genetic disorders that impair the body's ability to control blood clotting or coagulation, which is used to stop bleeding when a blood vessel is broken. Haemophilia A (clotting factor VIII deficiency) is the most common form of the disorder, occurring at about 1 in 5,000-10,000 male births. Haemophilia B (factor IX deficiency) occurs at about 1 in about 20,000-34,000 male births. Similarly to most recessive sex-linked, X chromosome disorders, haemophilia is more likely to occur in males than females. This is because females have two X chromosomes while males have only one, lacking a 'back up' copy for the defective gene; meaning, the defective gene is guaranteed to manifest in any male who carries it. Because females have two X chromosomes and because haemophilia is rare, the chance of a female having two defective copies of the gene is very low, thus females are almost exclusively asymptomatic carriers of the disorder.