Cheers for science freelancer Baskin for writing so lucidly and comprehensively about a field where yesterday's research idea is tomorrow's patented production technique. Her focus: how genetic engineering techniques are being utilized to study, treat, and prospectively prevent genetic disease. Historically, she turns to the early insights of Sir Archibald Garrod, who coined the term ""inborn error of metabolism"" to describe certain familial diseases; Mendel's ""factors"" of inheritance, he reasoned, might explain each individual's chemical uniqueness. Today, there are over 35,000 catalogued genetic diseases, as well as a major grouping of multi-factoral illnesses (diabetes, heart disease, schizophrenia) where genes and environmental factors interact. Having led readers gently through the past, Baskin plunges into a detailed explanation of the theory and practice of gene isolation, analysis, and synthesis--work that has recently earned a plethora of Nobel prizes. Here she is remarkably on top of the field. Thus, she describes an approach being taken to locate the defective gene in certain hereditary diseases through the identification of nearby fragments of DNA that act as markers--ones that in all likelihood will be inherited along with the disease gene in question. The marker genes have to be ""polymorphic"" (i.e., existing in several varieties), while the family pedigree studies have to be large enough to provide scores of blood samples to see ff potential markers distinguish between relatives with and without the disease. Since completion of her manuscript, that very technique has paid off in locating a marker for the devastating neurological disorder Huntington's Disease. Baskin also describes attempts at gene replacement therapy--including the controversial case of the California scientist who treated European and Israeli patients for an inherited blood disorder. The therapy didn't work (for reasons Baskin suggests), but appeared to do no harm either. Baskin uses such material as a spring-board for a good solid discussion of the ethical and value issues raised by genetic intervention. Not an easy book by any means, but well worth the effort for the knowledge conveyed.