鐮刀型紅血球疾病

title: 类型和术语.
content: 「镰刀型细胞贫血症」是一种特定类型的镰刀型红血球疾病的名称,其病因在于同型合子而产生了Hgb S的突变。其他类型的包括:  和镰刀型细胞贫血症不同,其他类型的镰刀型红血球疾病的病因在于异型结合,使得一个复制成导致Hgb S的突变,一个复制成异常的血红蛋白基因。必须要知道的是,「镰刀型细胞贫血症」是「镰刀型红血球疾病」一特定类型的名称,而「镰刀型红血球疾病」则不是。因为不同类型的镰刀型红血球疾病都极不一样,所以必须在治疗前,先分辨出疾病的确切类型。
title: 征兆及症状.
content: 罹患了镰刀型细胞贫血症的人会有激烈变化的贫血症,和一般血红蛋白浓度为6-9 g/dl相比。网织红血球的数量开始提升,反映了新的红血球细胞在取代快速遭破坏的旧细胞,红血球的生命周期被此一疾病明显地缩短了。通常,白血球和血小板的数量也会提升,并可能因此导致血管阻塞。
title: 血管阻塞危机.
content: 血管阻塞危机是由于镰刀型红血球细胞会阻塞毛细血管而限制流至器官的血量,因而导致局部缺血、疼痛和器官的伤害。  因为脾脏细小的血管和负有清除不良红血球的功能,所以常常会被影响到,通常在患者儿童期末期前便会形成梗塞。这种自体脾脏移除(autosplenectomy)会增加被encapsulated organisms感染的风险,对于这类脾功能缺乏者,预防性的抗生素和接种都被建议要有的。肝衰竭也有可能渐渐地出现。  骨头,尤其是支撑体重的骨头,也常是血管阻塞伤害的主要目标之一。如此会导致缺血性坏死(尤其是在股骨部位)和骨头退化。患者感觉到的疼痛也是源于骨头梗塞。
title: 疾病遗传学.
content: 通常人体内会存在由两个α链、两个β链组成的血红蛋白A,由两个α链、两个δ链组成的血红蛋白A2,以及由两个α链、两个γ链组成的血红蛋白F。其中,新生儿在六周以前,体内主要以血红蛋白F为主,而出生六周以后则主要为血红蛋白A。在被诊断为镰刀型红血球疾病的患者中,至少一个拷贝的β珠蛋白被镰刀型血红蛋白(Hb S)替代。在最常见的镰刀型红血球疾病,即镰状红血球贫血症患者中,两个拷贝的β珠蛋白均被镰刀型血红蛋白(Hb S)替代。  镰刀型红血球为常染色体隐形遗传疾病。一个人从父母遗传得到的血红蛋白基因决定了他(她)血液中含有哪种血红蛋白。如果父母二人中一人为镰状红血球贫血患者,而另一人为镰状红血球基因携带者,则子女有50%的概率患有镰状红血球贫血疾病,50%的概率为镰状红血球基因携带者。如果父母二人均为镰状红血球基因携带者,则子女有25%的概率患有镰状红血球贫血疾病, 25%的概率携带正常血红蛋白基因,以及50%概率为镰状红血球基因携带者  疟原虫生活史会侵入红血球中发育。疟原虫会导致镰刀型红血球过早破裂,使得疟原虫不能繁殖。此外,聚合的血红素影响寄生虫消化血红素的能力。因此在疟疾疫区,镰状红血球基因携带者较容易存活。  限制性片段长度多态性分析显示,镰刀型血红蛋白基因突变很可能源于多个地域。这些突变单倍型通常由地名命名:喀麦隆、塞内加尔、贝宁,、班图、以及沙特-亚洲。由于一些单倍型携带者, 例如塞内加尔与沙特-亚洲单倍型患者,体内通常可检测到较高水平的血红蛋白F,这些患者的病症相对较轻。这也是对单倍型的研究对临床的贡献之处。

Summary: 镰刀型红血球疾病(英语:Sickle-cell disease, SCD)是一组通常由双亲遗传而来的血液疾病。其中最常见的一种类型,叫做镰状红血球贫血症(Sickle-cell anemia, SCA)。该疾病会引起红血球中的载氧血红蛋白异常。在某特定的情况下(通常是缺氧状况),红血球会变成坚硬的镰刀型 。镰刀状红血球疾病的问题通常会在五到六个月龄时发作。患者可能会出现多项健康问题,例如突发的疼痛(镰刀型贫血危机,sickle-cell crisis)、贫血、细菌感染与中风。当患者年纪稍长之后可能会出现慢性疼痛。在已开发国家中的患者平均寿命为40到60岁。

Sickle cell disease: Sickle cell disease (SCD) is a group of blood disorders typically inherited from a person's parents. The most common type is known as sickle cell anaemia (SCA). It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells. This leads to a rigid, sickle-like shape under certain circumstances. Problems in sickle cell disease typically begin around 5 to 6 months of age. A number of health problems may develop, such as attacks of pain ("sickle cell crisis"), anemia, swelling in the hands and feet, bacterial infections and stroke. Long-term pain may develop as people get older. The average life expectancy in the developed world is 40 to 60 years. Sickle cell disease occurs when a person inherits two abnormal copies of the β-globin gene that makes haemoglobin, one from each parent. This gene occurs in chromosome 11. Several subtypes exist, depending on the exact mutation in each haemoglobin gene. An attack can be set off by temperature changes, stress, dehydration, and high altitude. A person with a single abnormal copy does not usually have symptoms and is said to have sickle cell trait. Such people are also referred to as carriers. Diagnosis is by a blood test, and some countries test all babies at birth for the disease. Diagnosis is also possible during pregnancy. The care of people with sickle cell disease may include infection prevention with vaccination and antibiotics, high fluid intake, folic acid supplementation, and pain medication. Other measures may include blood transfusion and the medication hydroxycarbamide (hydroxyurea). A small percentage of people can be cured by a transplant of bone marrow cells. As of 2015, about 4.4 million people have sickle cell disease, while an additional 43 million have sickle cell trait. About 80% of sickle cell disease cases are believed to occur in Sub-Saharan Africa. It also occurs relatively frequently in parts of India, the Arabian Peninsula, and among people of African origin living in other parts of the world. In 2015, it resulted in about 114,800 deaths. The condition was first described in the medical literature by American physician James B. Herrick in 1910. In 1949, its genetic transmission was determined by E. A. Beet and J. V. Neel. In 1954, the protective effect against malaria of sickle cell trait was described.