This is because the process called hemostasis, literally meaning to stop the flow of blood, is impaired.

这是因为友病患者的止过程受损，即其凝功能出现障。

And also how he knows exactly that he's a hemophiliac.

还有他是如何确切知道自己是友病患者的。

Most are designed to target rare genetic diseases, including haemophilia B, where mutation causes problems with blood clotting.

大多数药物旨在针对罕见的遗传疾病，包括 B 型友病，这种疾病的突变会导致凝问题。

Treatment for hemophilia A and B are done with injections of the missing or nonfunctional clotting factor.

治疗友病A和B的方法通常是注射那些缺失或失活的凝因子。

In the family of disorders known as hemophilia, a patient can usually complete the first two steps of hemostasis just fine, but they can't make an effective fibrin clot.

在被称为友病的疾病家族中，病人通常可以很好地完成止的前两个步骤，但是他们不能制有的纤维蛋白凝块。

Believe it or not, this is a somewhat simplified version of the coagulation cascade; but, it contains all of the key parts needed to understand hemophilia.

总之，这就是简化版的凝级联反应，已经包含了理解友病病理所需的关键部分。

To prevent complications from an existing blood or bleeding disorder, such as sickle cell disease, thalassemia, or anaemia caused by kidney disease, haemophilia, or von Willebrand disease.

预防现有液或出性疾病的并发症，如镰状细胞病、地中海贫或由肾脏疾病、友病或管性友病引起的贫。

By far the most common of these are deficiencies of factor VIII which gives rise to factor VIIIa and is stabilized by another factor called von Willebrand factor.

目前为止，大多数的友病通常是因子VIII缺乏症；因子VIII能转变为因子VIIIa，并被管性友病因子（vWF）固定。

Signs and symptoms hemophilia A and B are nearly clinically identical, which makes sense since factors VIIIa and IXa work together in the coagulation cascade to activate factor X.

友病A和B的体征和症状在临床上几乎相同，也说得通，因为因子VIIIa和IXa在凝级联反应中，共同作用以激活因子X。

Diagnosis of hemophilia A and B usually starts with lab tests including a platelet count which is usually normal, a prothrombin (PT) time, and a partial thromboplastic (PTT) time.

友病A和B的诊断通常是进行实验检测，包括小板计数（一般正常）、凝酶原时间（PT），以及部分凝活酶时间（PTT）。