Causes of haemophilia

Most haemophilia is inherited. Some gene changes are new. Acquired haemophilia is a different story altogether.

Inherited haemophilia A and B

In inherited haemophilia, a change in the factor VIII or factor IX gene means the body does not make enough working factor. The gene sits on the X chromosome.

A parent can carry the gene without knowing. Daughters may carry; sons may be affected. Family history helps diagnosis but is not always present.

When there is no family history

About one in three children with haemophilia has no known family history because the gene change is new in that child. Parents should not blame themselves for a mutation no one could see in advance.

Testing still matters for siblings and future pregnancy planning. The centre or genetics service can explain what to test and when.

Carriers and women who bleed

Because women have two X chromosomes, many carriers have enough factor to feel well. Lyonization and other patterns can leave a woman with factor levels in the haemophilia range.

Heavy periods, bleeding after childbirth, and bleeding after dental work in women in haemophilia families deserve testing, not dismissal.

Acquired causes are different

Acquired haemophilia is not passed to children the same way. It needs urgent specialist care and inhibitor testing. If someone tells you all haemophilia is ‘from the family’, that is not true of acquired cases.

This page is general information from Nepal Hemophilia Society. It is not a diagnosis or a treatment plan. A bleed, a head injury, or bleeding after an accident needs urgent hospital care. Ask your treatment centre before you change any treatment.