A gene is the basic physical and functional unit of heredity. Genes, which are made up of

DNA, act as instructions to make molecules called proteins. The terms dominant and

recessive describe the inheritance patterns of certain traits. That is, they describe how

likely it is for a certain phenotype to pass from parent offspring. A dominant allele

produces a dominant phenotype in individuals who have one copy of the allele, which can

come from just one parent. For a recessive allele to produce a recessive phenotype, the

individual must have two copies, one from each parent. An individual with one dominant

and one recessive allele for a gene will have the dominant phenotype. They are generally

considered “carriers” of the recessive allele: the recessive allele is there, but the recessive

phenotype is not.

Genetic counselling is a communication process, which aims to help individuals, couples

and families understand and adapt to the medical, psychological, familial and reproductive

implications of the genetic contribution to specific health conditions.

This process integrates the following:Interpretation of family and medical histories to assess the chance of disease occurrence or recurrence.Education about the natural history of the condition, inheritance pattern, testing, management, prevention, support resources and research.Counselling to promote informed choices in view of risk assessment, family goals, ethical and religious values.Support to encourage the best possible adjustment to the disorder in an affected family member and/or to the risk of recurrence of that disorder. The purpose of genetic counseling is to inform at-risk individuals about the relevant genetic, biological and environmental risk factors related to the individual's inherited syndrome or cancer. Genetic counseling involves pre-test and post-test counseling. Pre-test counseling focuses on informed consent. An individual is educated on why the test is being offered and is informed on the possible outcomes and accuracy of a test. Post-test counseling involves the disclosure of test results, a discussion of the significance of the results, and follow-up plans for the patient.

Genetic testing should be performed by a genetic counselor, with specialized education, training and experience in medical genetics and counseling. It is the job of a genetic counselor to obtain and assess relevant information concerning an individual's risk and to provide information and support to families and individuals who may be at increased risk for a variety of inherited predispositions. A genetic counselor should be able to explain how family history and laboratory testing provide an adjusted risk for developing cancer and provide a clear explanation of the risk for cancer development, along with the preventative, screening and diagnostic processes that are available to the patient based on the adjusted risk.