what chromosome are affected by hemophilia
A defect in one of the genes that determines how the body makes blood clotting factor VIII or IX causes hemophilia. These genes are located on the X chromosomes (KRO-muh-somz). Chromosomes come in pairs. Females have two X chromosomes, while males have one X and one Y chromosome. Only the X chromosome carries the genes related to clotting factors. A male who has a hemophilia gene on his X chromosome will have hemophilia. When a female has a hemophilia gene on only one of her X chromosomes, she is a hemophilia carrierâ and can pass the gene to her children.