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医学遗传学 17 出生缺陷eng v.ppt

发布:2016-07-27约7.89千字共68页下载文档
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17 出生缺陷 Birth Defects; Birth defects are defined as abnormalities of structure, function, or body metabolism that are present at birth. ;1. General; However, most babies are born without problems, while most of those who are can have treatment that will make them much better, or even allow them to lead a normal life. ; Understanding the nature and causes of birth defects can help reduce the mystery, fear and guilt often associated with them.; An international monitoring programme shows that, across Europe, just over 2 per cent of babies are discovered at birth to have a defect that will affect their ability to survive or function normally. ; Some defects are often not discovered until later (eg deafness and problems in walking). ; There is considerable regional variation in the rate of defects seen at birth. Glasgow and Dublin have traditionally been black spots, with rates over 3 per cent, but these figures are falling. ; The number of babies actually born with defects is also markedly affected by the availability of prenatal screening, and the availability of voluntary termination of pregnancy in the case of severe abnormalities. ;2. Forms of Birth Defects; The most common kinds of defect are those affecting the limbs (arms and legs). These include missing or extra fingers or toes, deficiencies in limb length, and abnormalities in positioning, such as club foot. ; Heart abnormalities represent the next most common category of defect. Common heart defects include holes in the heart where blood can pass from one side of the heart to the other. Again, these may not all be detected at birth. ; The third most common kind of defect affects the spinal cord, such as spina bifida. ; Other defects commonly observed include those affecting the face (such as cleft lip and palate), problems with the development of the intestines and stomach, and problems affecting the sexual organs. ;
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