出血失调

Hemophilia is usually an inherited bleeding disorder in which the blood does not clot properly. This can lead to spontaneous bleeding as well as bleeding following injuries or surgery. Blood contains many proteins called clotting factors that can help to stop bleeding. People with hemophilia have low levels of either factor VIII (8) or factor IX (9). The severity of hemophilia that a person has is determined by the amount of factor in the blood. 因子的量越低, the more likely it is that bleeding will occur which can lead to serious health problems.
 

在极少数情况下，一个人可能会在以后的生活中患上血友病.  大多数病例涉及中老年人, or young women who have recently given birth or are in the later stages of pregnancy.  这种情况通常通过适当的治疗来解决.
 

原因

血友病是由 突变 或改变, 在其中一个基因中, that provides instructions for making the clotting factor proteins needed to form a blood clot. This change or 突变 can prevent the clotting protein from working properly or to be missing altogether. 这些基因位于X染色体上. Males have one X and one Y chromosome (XY) and females have two X chromosomes (XX). Males inherit the X chromosome from their mothers and the Y chromosome from their fathers. 雌性从双亲各继承一条X染色体.

The X chromosome contains many genes that are not present on the Y chromosome. This means that males only have one copy of most of the genes on the X chromosome, 而女性有2个拷贝. 因此, males can have a disease like hemophilia if they inherit an affected X chromosome that has a 突变 in either the factor VIII or factor IX gene. 女性也可能患有血友病，但这种情况要少见得多. In such cases both X chromosomes are affected or one is affected and the other is missing or inactive. In these females, bleeding symptoms may be similar to males with hemophilia.
 

有一条受影响的X染色体的女性是血友病的“携带者”. 有时携带病毒的女性会出现血友病的症状. 除了, she can pass the affected X chromosome with the clotting factor gene 突变 on to her children. 了解更多有关 血友病的遗传模式.
 

尽管血友病是家族遗传, some families have no prior history of family members with hemophilia. Sometimes, there are carrier females in the family, but no affected boys, just by chance. 然而, 大约三分之一的时间, the baby with hemophilia is the first one in the family to be affected with a 突变 in the gene for the clotting factor.
 

血友病可导致:

• Bleeding within joints that can lead to chronic joint disease and pain
• Bleeding in the head and sometimes in the brain which can cause long term problems, 比如癫痫发作和瘫痪
• Death can occur if the bleeding cannot be stopped or if it occurs in a vital organ such as the brain.

血友病有几种不同的类型. 以下两种是最常见的:

• 血友病A(典型血友病)
  这种类型是由凝血因子VIII的缺乏或减少引起的.
• 血友病B(圣诞病)
  这种类型是由凝血因子IX缺乏或减少引起的.

体征和症状

血友病的常见症状包括:

• 关节出血. This can cause swelling and pain or tightness in the joints; it often affects the knees, 肘部, 和脚踝.
• Bleeding into the skin (which is bruising) or muscle and soft tissue causing a build-up of blood in the area (called a hematoma).
• Bleeding of the mouth and gums, and bleeding that is hard to stop after losing a tooth.
• Bleeding after circumcision (surgery performed on male babies to remove the hood of skin, 叫做包皮, 盖住阴茎的头部).
• 注射后出血，如接种疫苗后出血.
• 难产后婴儿头部出血.
• 尿液或粪便中带血.
• 频繁且难以止住的流鼻血.

谁受到影响

每5000名男婴中就有1人患有血友病. Currently, about 20,000 males in the United States are living with the disorder. A型血友病的发病率是B型血友病的四倍, 大约一半的患者有严重的症状. 血友病影响所有种族和民族群体的人.
 

诊断

Many people who have or have had family members with hemophilia will ask that their baby boys get tested soon after birth.

关于 one-third of babies who are diagnosed with hemophilia have a new 突变 not present in other family members. 在这些情况下, a doctor might check for hemophilia if a newborn is showing certain signs of hemophilia.
进行诊断, doctors would perform certain blood tests to show if the blood is clotting properly. 如果没有, 然后他们会做凝血因子测试, 也叫因子分析, 诊断出出血性疾病的原因. 这些血液检查可以显示血友病的类型和严重程度.
 

治疗

The best way to treat hemophilia is to replace the missing blood clotting factor so that the blood can clot properly. This is done by infusing (administering through a vein) commercially prepared factor concentrates. People with hemophilia can learn how to perform these infusions themselves so that they can stop bleeding episodes and, 通过定期进行注射(称为预防), 甚至可以预防大多数出血发作吗.

Good quality medical care from doctors and nurses who know a lot about the disorder can help prevent some serious problems. Often the best choice for care is to visit a comprehensive Hemophilia 治疗 Center (HTC). An HTC not only provides care to address all issues related to the disorder, but also provides health education that helps people with hemophilia stay healthy.
 

抑制剂

关于 15-20 percent of people with hemophilia develop an antibody (called an inhibitor) that stops the clotting factors from being able to clot the blood and stop bleeding. 出血发作的治疗变得极其困难, and the cost of care for a person with an inhibitor can skyrocket because more clotting factor or a different type of clotting factor is needed. People with inhibitors often experience more joint disease and other problems from bleeding that result in a reduced quality of life.