Introduction Complexity of predictive and prenatal testing for neurogenetic late-onset diseases

When predictive testing and prenatal testing for Huntington’s disease (HD) became a reality, about 15 years ago, this was an important milestone in medical history and a new challenge for families and professionals. Since then, many predictive and prenatal tests have been performed, initially indirectly using DNA linkage and since 1993 using direct mutation analysis. Moreover, increasing knowledge about the human genome has resulted in the availability of predictive tests and prenatal tests for other neurogenetic diseases and hereditary cancers. The topic of genetic testing for hereditary cancers is beyond the scope of this book, in which the focus is on prenatal testing for neurogenetic late-onset disease. However, predictive testing for neurogenetic late-onset disease receives attention in several chapters of this book because of its special relationship with prenatal testing.