World Hemophilia Day 2022: Why hemophilia rare in women?
Hemophilia is a hereditary bleeding disorder that mainly affects men. In this condition, the blood clotting proteins are missing and one bleeds for longer than normal after an injury. Because of problems in clotting, hemophilia can be life threatening in cases when bleeding cannot be stopped for some reason or it occurs in brain or some other vital organ. Bleeding in head can lead to seizures or paralysis.
What is the cause of hemophilia?
When blood moves through blood vessels, it has a natural tendency to keep itself in fluid status but in case of injury to the vessels, there is a clot formation which prevents loss of blood. The clot formation is a complex process which involves clotting factors and platelets. When these clotting factors are missing due to mostly genetic reasons this disease occurs. Hemophilia can be acquired too in case of certain conditions when a person's immune system attacks clotting factos in the blood. Pregnancy, autoimmune conditions, multiple sclerosis, cancer or drug reactions can cause it.
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Symptoms of hemophilia
According to mayoclinic, unexplained and excessive bleeding from cuts or injuries, large or deep bruises, unusual bleeding after vaccinations, pain, swelling or tightness in joints, blood in urine or stool, nosebleeds without a known cause are some of the symptoms of hemophilia.
Why hemophilia is rare in women
"Hemophilia is a X linked recessive disorder. It means the gene for hemophilia lies on the X chromosome. Since females have two X chromosomes, they are usually not affected by hemophilia," says Dr. Shweta Bansal, Consultant Pediatric Oncologist, Masina Hospital.
Women, however, can be the carriers of the disease and pass on the disease to their sons. Since males have only one X chromosome, they can manifest the disease in the absence of normal gene.
According to Dr Bansal, hemophilia can affect women in the following cases:
Lyonisation of X chromosome: There is inactivation of one of the X chromosome with normal wild type gene and only affected chromosome with hemophilia gene is expressed.
When both X chromosomes are affected: The condition is called called homozygosity. If the mother is carrier and father is affected with the disease, then daughter can inherit both affected X chromosomes from each parent and will manifest the disease.
Other reason could be denovo new mutation in the normal X chromosome , making both chromosomes having defective gene.
Turner syndrome: In women affected by it, one of the X chromosome is missing and in case the X chromosome is afected, they can manifest the disease.
Deficiency of vitamin K: Vitamin K helps in activation of coagulation factors. Deficiency of Vitamin K also leads to hemophilia like state.
