Hello and welcome to the zero to finals podcast. My name is Tom and in this episode I'm going to be

talking to you about hemophilia. And if you want to follow along with written notes on this topic,

you can follow along at zero definals.com slash hemophilia or in the hematology section of the

zero to finals medicine book.

So let's get straight into it.

Hemophilia A and hemophilia B are inherited severe bleeding disorders.

Hemophilia A is caused by a deficiency in factor 8, which is a type of clotting factor,

and hemophilia B, which is also known as Christmas disease, is caused by a deficiency in a different clotting factor, factor 9. So remember,

hemophilia A is factor 8 deficiency, and hemophilia B is factor 9 deficiency. Both hemophilia A and B are X-linked recessive, and this is a type of

genetic inheritance, which is X-linked. And this means that in order to have the condition,

all of the X chromosomes inside a person's cell need to have the abnormal gene. I remember that

men only have a single X chromosome and women have two.

Therefore, men only require one abnormal copy in order to have the condition,

because they only have one X chromosome.

If women have an abnormal copy, they also have another normal chromosome, so they're not affected by the

condition and they become a carrier of the condition. So basically, hemophilia A and B almost exclusively

affect males. It would be very unusual for a female to be affected because they would need

an affected father and also a mother that's a carrier of the

condition or who has a condition herself. And that way they may be able to pick up two abnormal

copies of the X chromosome. However, this is quite unlikely. So what are the signs and symptoms? Well,

both hemophilia A and B are severe bleeding disorders. And this means that patients can bleed excessively

in response to only minor trauma. And there's also a risk of spontaneous hemorrhage without any trauma.

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