普瑞德威利症候群

title: 成因.
content: 这种病的病因肇因于第15号染色体印迹基因区的基因缺陷,且此基因缺陷来自父亲,或同时拥有两条来自母亲的第15号染色体。若此基因缺陷来自母亲,又或者两条第15号染色体皆来自父亲,则会造成天使人症候群(Angelman's syndrome)。
title: 症状.
content: 患有此症的人外型特征有发色较淡、杏仁眼、发展迟缓、性功能发育不全等。从婴幼儿期就有体温调节差的问题,容易发烧,容易并发喉头软化症。且因为无法控制饮食,也容易有身体过度肥胖,并发血糖过高、酮酸中毒等疾病。
title: 出生时.
content: 出生时此症的婴儿皮肤较为苍白,且有肌肉低张力与手掌、脚掌较小的现象,男性可能出现双侧隐睪。由于吸吮有些困难,因此在一岁前,此症婴儿较正常婴儿瘦弱。
title: 两岁后.
content: 肌肉低张力较为改善,但是开始产生此症的典型症状─拼命地吃,无法取得饱足感,且会产生情绪不稳的现象。尽管此症的儿童拥有正常的语言能力,但是实质智能较一般人为低(一般人平均IQ为100,此症患者平均为70)
title: 其他事项.
content: 小胖威利变异的染色体为15q11-q13,日-月-年的日期写法正好是15/11/13,所以国际小胖威利协会将这一天订为「小胖威利国际宣导日」,百年才一次。
title: 参考文献.
content: 《一首摇滚上月球》

Summary: 普瑞德威利症候群(俗称威利症,英文名Prader-Willi syndrome,PWS)是一种肇因于特定基因功能丧失的遗传性疾病 。新生儿患者会出现包括肌肉无力、进食不良及发育迟缓的症状 。患者从童年开始即会不断的有饥饿感,并常因过度进食而导致肥胖和第2型糖尿病,也常伴随着轻至中度的智力障碍和行为异常问题 。患者在外观上常见前额狭窄、手脚短小、身高矮小、浅肤色等特征,且无法生育 。 统计显示约有74%的患者的父系染色体有部分缺失,另25%的患者则是出现2条母系染色体,但无父系染色体 。 因为母亲的第15号染色体有部分功能是关闭的,故患者最后获得的基因无法发挥作用 。此症通常不会遗传,而是在卵子、精子或胚胎早期发育的过程中发生突变,目前没有已知的风险因子。育有罹患此症子女的父母下一胎再生下相同子女的几率不到1%。 天使综合症(Angelman syndrome)的致病机制与此症相似,是自母亲处遗传了有缺陷的第15号染色体,或是直接从父亲处遗传到了2条第15号染色体。 此症无法治愈 。但接受治疗可以改善病情,尤其是早期发现早期治疗。新生儿患者的喂食困难可以使用喂养管辅助,3岁开始即需接受长期的严格饮食控制以及运动课程,使用生长激素也有助改善预后。接受咨询和药物治疗可能有助于解决患者的部分行为问题。患者成年后,通常需要居住在相关的照护机构内

Prader–Willi syndrome: Prader–Willi syndrome (PWS) is a genetic disorder caused by a loss of function of specific genes on chromosome 15. In newborns, symptoms include weak muscles, poor feeding, and slow development. Beginning in childhood, those affected become constantly hungry, which often leads to obesity and type 2 diabetes. Mild to moderate intellectual impairment and behavioral problems are also typical of the disorder. Often, affected individuals have a narrow forehead, small hands and feet, short height, light skin and hair, and are unable to have children. About 74% of cases occur when part of the father's chromosome 15 is deleted. In another 25% of cases, the affected person has two copies of chromosome 15 from their mother and none from their father. As parts of the chromosome from the mother are turned off through imprinting, they end up with no working copies of certain genes. PWS is not generally inherited, but rather the genetic changes happen during the formation of the egg, sperm, or in early development. No risk factors are known for the disorder. Those who have one child with PWS have less than a 1% chance of the next child being affected. A similar mechanism occurs in Angelman syndrome, except the defective chromosome 15 is from the mother, or two copies are from the father. Prader–Willi syndrome has no cure. Treatment may improve outcomes, especially if carried out early. In newborns, feeding difficulties may be supported with feeding tubes. Strict food supervision is typically required, starting around the age of three, in combination with an exercise program. Growth hormone therapy also improves outcomes. Counseling and medications may help with some behavioral problems. Group homes are often necessary in adulthood. PWS affects between 1 in 10,000 and 1 in 30,000 people. The condition is named after Swiss physicians Andrea Prader and Heinrich Willi who, together with Alexis Labhart, described it in detail in 1956. An earlier description was made in 1887 by British physician John Langdon Down.