Book excerpt: Neurogenetics is intended for any physician or scientist who manages patients with inherited diseases of the nervous system. It presents the clinical phenotypes of the most commonly inherited neurologic diseases, and their molecular pathogenesis, followed by a description of the appropriate tests to be used in diagnosis. Two introductory chapters familiarize the nongeneticist with medical genetic terminology and molecular genetic techniques useful in the analysis of genetic disease and genetic testing. Subsequent chapters examine major neurologic disorders caused by single defects, as well as disease phenotypes such as Alzheimer disease or amyotrophic lateral sclerosis which may be caused by defects in single genes, but may also be seen as sporadic diseases. The genetic components of other common neurologic disorders, such as epilepsy, multiple sclerosis, migraine, and stroke are all covered in detail. The final chapter discusses genetic counseling of symptomatic and pre-symptomatic individuals. Throughout, chapters discuss genotype/phenotype correlations and, where appropriate, animal models for inherited human neurologic diseases. Several chapters are devoted to recently discovered diseases caused by unstable DNA repeats. Special emphasis is placed on conveying how DNA testing can be applied to the daily practice of geneticists and neurologists.