Bleeding disorders are generally passed from parent to child at the time of conception. For women with bleeding disorders, this is no different. Each cell of the body contains structures called chromosomes. A chromosome is a long chain of chemicals known as DNA. This DNA is arranged into about 30,000 units called genes. These genes determine such things as the colour of a person’s eyes. In the case of most factor deficiencies, one of these genes has a defect. The defective gene that causes a factor deficiency is usually on a chromosome, which does not decide the sex of the child. This means the bleeding disorder is an autosomal inherited pattern and can affect females as well as males. The majority of bleeding disorders have an autosomal inheritance pattern. These are factors I, II, V, VII, X, XI, XII, XIII. vWD and platelet function disorders also follow this pattern. When the defective gene that causes a factor deficiency is on the chromosome that does decide the sex of a child it is known as a sex-linked inheritance pattern. The sex-linked pattern only applies to haemophilia A and haemophilia B.