And this deficiency is called hemophilia A (or classic hemophilia).

这种缺乏症也称作友病A（甲型友病）或者经典友病。

Alexei, the heir to the throne, had a life-threatening blood disease called hemophilia.

阿列克谢是王位的继承人，得友病，这是一种可能会致死的液疾病。

Today, we know that the doctors had prescribed aspirin, a drug that worsens hemophilia.

今，我们知道生开的处方是阿司匹林。这种药会让友病恶化。

An insufficient concentration or decreased activity of any coagulation factor can cause hemophilia, except factor XII deficiency which is asymptomatic.

任何凝因子的浓度不够或者活性降低都会引起友病，一个例外是缺乏因子XII的话，不会有相关症状出。

The youngest of five children, he was born with hemophilia (when blood doesn’t clot).

是五个孩子中最小的一个， 生来就患有友病（当液不凝固时）。

He needs the fluid drained, but because of his hemophilia, I could kill him trying to save him.

需要排出液体，但由于患有友病，我可以为救而杀。

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

治疗友病A和B的方法通常是注射缺失或失活的凝因子。

For hemophilia A, desmopressin, also called DDAVP (1-deamino-8-D-arginine vasopressin) is helpful for patients with mild, quantitative factor VIII deficiency.

对于友病A，去氨加压素（DDAVP）有助于治疗轻症因子VIII数量缺乏。

Finally, it's best for individuals with hemophilia to avoid contact sports and medicines that promote bleeding, like aspirin.

最后对于友病患者来说，最好避免接触性运动，不用促进流的药物，如阿司匹林。

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，已经包含理解友病病理所需的关键部分。

Also, vitamin K deficiency can cause hemophilia since vitamin K is needed by the liver to synthesize and release factors II, VII, IX, and X.

并且维生素K缺乏症也可引起友病，因为维生素K参与肝脏合成及释放因子II、VII、IX和X。

To confirm hemophilia A or B, tests to look at specific factor activities, and mutation testing of the genes encoding them, can be done.

为确诊友病A或B，可以检测特定因子的凝活性或进行基因诊断。

Disorders that are associated with mutations of X chromosome genes, like color blindness, or hemophilia, are often less severe in individuals with two X chromosomes.

与 X 染色体基因突变相关的疾病，如色盲或友病，在具有两条 X 染色体的个体中通常不太严重。

Now, a mimic of hemophilia A is von Willebrand disease, which is an inherited problem with primary hemostasis caused by a deficiency of von Willebrand factor.

还有一种类友病A，即管性友病，是一种遗传性的初级止障碍，由管性友病因子（vWF）缺乏引起。

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，但是们不能制造有效的纤维蛋白凝块。

Another common deficiency is deficiency of factor IX, called hemophilia B (which used to be called Christmas disease, named after the first patient who had it, not the holiday).

另一种常见的缺陷是因子IX缺乏症，称作友病B（乙型友病），以前也称作Christmas病，是以第一个被报道的病患命名，而不是指圣诞节。

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）。

In most cases of hemophilia there is a decrease in the amount or function of one or more of the clotting factors that makes secondary hemostasis less effective and allows more bleeding to occur.

在大多数友病中，都有一种或多种凝因子在数量上减少或功能上减弱，使次级止过程的功效下降，而出更多。

Women with one mutated gene copy have a remaining healthy copy, so they don't get hemophilia unless X-chromosome inactivation turns off the normal copy in the majority of cells.

携带一个突变基因的女性还有一个健康的基因拷贝，所以她们一般不会患友病，除非X染色体失活使得大多数细胞中正常的基因拷贝沉默。