It is rather remarkable how many new tricks can be taught old dogs. The clinician who departed from the academic cloister more than 20 years ago has been obliged to learn a whole bagful. Among the many clinical spin-offs of the "new knowledge" generated in the laboratory is the fascinating world of cytogenetics. Practically overnight every practitioner has been thrust into the role of genetic counselor, often an uncomfortable and unfamiliar character. Questions from anxious parents, easily parried in the past by retreating behind our vast fund of ignorance, must now be answered. It represents an obligation of enormous importance.
So there has been a scramble to obtain valid information presented in a form that is comprehensible to those among us whose last contact with genetics was a dimly recalled vision of a gentle Austrian monk puttering amidst the sweet peas. There have been half a dozen fine books on