ABSTRACT
Cancer genetics forms a major part of genetics services and although the large majority of cases show only weak inherited influences, a small proportion show Mendelian inheritance, often with very high risks. Genetic counsellors play an important role in the delivery of cancer genetics services, especially in linking with the other health professionals involved and ensuring that extended families are fully informed and counselled. Genetic linkage studies in rare Mendelian tumour syndromes showed that the same loci are often involved as in sporadic tumours, indicating a direct relationship between the familial and non-familial forms of the same tumour type. Numerous oncogene loci are well recognised and are known to represent important growth factors or receptors involved in the regulation of cell division and other cell behaviours. The genes involved in the process are tumour suppressor genes, which play important roles in growth, development and cell-signalling pathways.
