In the current scientific climate, it is difficult to believe that the double helical structure of DNA was only described as recently as 1953 [1, 2], and that the correct number of human chromosomes was finally identified in 1956 . During the course of only one generation, karyotyping became a commonplace method of diagnosis of chromosomal abnormalities, and DNA studies were being used to offer families reproductive choices previously denied to them. Since the 1980s techniques in cytogenetics and molecular genetics have developed dramatically, adding to the information that is now accessible to families. As this new technology assumes more importance in everyday health care, the health professional has to have an understanding of its applications and limitations. The use of genetic technology is already moving from the confined area of medical genetics to almost every other speciality.