This Unit looks at three different uses of genetic testing: pre-natal diagnosis, childhood testing and adult testing. Such tests provide genetic information in the form of a predictive diagnosis, and as such are described as predictive tests. Pre-natal diagnosis uses techniques such as amniocentesis to test fetuses in the womb. For example, it is commonly offered to women over 35 to test for Down's syndrome. Childhood testing involves testing children for genetic diseases that may not become a problem until they grow up, and adult testing is aimed at people at risk of late-onset disorders, which do not appear until middle age. In addition, we address some of the issues involved in carrier testing, another predictive test. This involves the testing of people from families with a history of genetic disease, to find out who carries the gene, and who therefore might pass the disease onto their children even though they themselves are unaffected. Here the aim is to enable couples to make informed choices about whether or not to have children, and if so whether they might have a genetic disease studies 'proteins'. Starting with a simple analysis of the molecular make up, the Unit moves on to look at the importance of protein and how they are digested and absorbed. This study unit is just one of many that can be found on LearningSpace, part of OpenLearn, a collection of open educational resources from The Open University. Published in ePub 2.0.1 format, some feature such as audio, video and linked PDF are not supported by all ePub readers.