Practitioners of public health genetics need a working knowledge of the basic principles of genetic science, including not just the classical rules of inheritance but also how the genetic ‘programme’ is played out in the functions of cells, tissues and whole organisms. They also need an understanding of how genetic changes may be related to the development and progression of disease. The first part of this chapter is devoted to laying the groundwork in genetic science and medical genetics.

In this chapter we also introduce some of the basic features of deoxyribonucleic acid (DNA) technology, which has enabled scientists to study and manipulate the genetic material. The development of this technology has been the driving force behind the human genome project, which has now delivered a complete ‘reference sequence’ for the human genome and is rapidly moving forward in the task of assigning functions to genes and their products. It is the explosion of information arising from the human genome project, and from the ‘post-genomic’ sciences such as proteomics, functional genomics, comparative genomics and bioinformatics, that is providing the raw material and the impetus for the development of new approaches to the diagnosis, treatment and prevention of disease. These new opportunities for genetics in medicine will be discussed in Chapter 4.

Basic molecular genetics

In most organisms, the genetic material in each cell is the chemical DNA. The DNA molecule acts as a code to specify the synthesis of different proteins, which are responsible for carrying out the functions of the cell.