Prenatal diagnosis and genetic screening : community and service implications / a report of the Royal College of Physicians.

  • Royal College of Physicians of London.
Date:
1989
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Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Prenatal diagnosis and genetic screening : community and service implications / a report of the Royal College of Physicians. Source: Wellcome Collection.

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    DNA methods Twin pregnancies Timing of prenatal diagnosis Adrenoleukodystrophy a 1-Antitrypsin deficiency Congenital adrenal hyperplasia (21-hydroxylase deficiency) X-linked choroideremia X-linked chronic granulomatous disease Cystic fibrosis Dihvdropteridine reductase deficiency Duchenne/Becker muscular dystrophy Fragile X mental retardation“ Haemophilia A Haemophilia B Huntington's chorea Myotonic dystrophy Norrie disease Ornithine transcarbamylase deficiency Osteogenesis imperfecta Type IV Phenylketonuria Predisposition to hereditary retinoblastoma Adult polycystic kidney disease Sickle cell disease a-Thalassaemia ß-Thalassaemia Tuberose sclerosis Fetal sexing for X-linked conditions a Linkage data is still contradictory and considerable caution is necessary in this condition. 2.41 Methods for the examination and analysis of DNA are greatly increasing the range and accuracy of prenatal and carrier diagnosis for inherited diseases, and can be used on any tissue at any stage of embryonic development. The principles and methods have been reviewed by Weatherall [22]. The possibility of prenatal diagnosis using DNA techniques usually depends on family studies, and especially analysis of DNA from an affected relative. It is therefore of the utmost importance to ensure that DNA (eg from a blood sample) from individuals with confirmed or even suspected severe inherited diseases is stored, whether the disease concerned can be diagnosed at present or not, for the future benefit of other family members. 2.42 Inherited diseases that have been diagnosed prenatally using DNA methods are listed in Table 8. However, progress is so rapid that the list will lengthen between the writing and publication of this report. 2.43 All multiple pregnancies in which prenatal diagnosis is contemplated should at the onset be referred to expert centres. With modern ultrasound guidance it is usually possible to obtain material from each fetus, but sampling multiple preg nancies requires a very high level of skill. Counselling prior to prenatal diagnosis in twin pregnancies must include the possibility of discordant results in the two fetuses, and of failure to obtain a diagnostic sample from one fetus and the choices that will then have to be made. 2.44 In the past, when results were discordant, couples had to choose between aborting both fetuses even though one was healthy or continuing a pregnancy that was certain to produce one seriously affected infant. Most couples at risk for really severe abnormalities chose to terminate the pregnancy, but there can be few more distressing outcomes. Selective feticide of an affected fetus is now possible in both the second and first trimester of pregnancy [23, 24] and often allows the healthy fetus to come to term. However, such techniques should be attempted only at expert fetal medicine centres. 2.45 Prenatal diagnosis should be carried out as early in pregnancy as possible for both pragmatic and moral reasons. Therefore, general practitioners need to be sufficiently aware of the indications to refer at-risk women early in the first trimester, and women should be encouraged to contact their GP early in pregnancy.