Genetics Flashcards
Why is it important for clinical practice to understand genetics?
Education, information provision, resource knowledge.
Assess risk factors.
Collecting patient and family history information.
Prevention and risk reduction.
Enhance own understanding.
Collaborate and communicate with interdisciplinary team.
What is the definition of genetics?
The study of individual genes.
What is the definition of genomics?
The study of all genes in the human genome together, their interaction with each other, the environment and the influence of other psychosocial and cultural factors.
What are chromosomes?
Inherited material that determines human characteristics
Consist of DNA – double stranded helix
Where are chromosomes found?
Found in the nucleus of each cell.
How many chromosomes do humans have?
46 chromosomes in 23 pairs
What are the four chemical bases of genes?
Adenine
Guanine
Cytosine
Thymine
What are some indicators of pre-disposition genetically for cancer?
Family history
Individual genetic make-up
Cancer occurring at a younger age than expected
More than one primary cancer in one person
Autosomal dominant inheritance (two or more generations affected, male and female)
Bilateral cancer in any paired organ
Pattern of cancer associated with a known cancer syndrome
Cancers occurring more frequently in a family than by chance (with absence of environmental/lifestyle factors)
Multifocal cancers in an organ
Cluster of the same cancer in close relatives.
How are genetic studies related to reducing cancer risk?
Epidemiological studies in large populations are being used to identify lifestyle elements.
Targeted health promotion activities.
Medical interventions are also utilized for risk reduction eg. surgical procedures like prophylactic mastectomy and colectomy
What are some of the concerns around genetic testing for cancer?
Genetic testing is stringently regulated – has ethical, legal and social implications
Many factors influence an individual’s decision to undergo genetic testing
Consequences may have wide reaching ramifications for the individual and their existing and future families
Genetic testing can provide an estimation of risk leading to uncertainty
Individuals need to decide whether to disclose results
Emotional, psychological and physical well being are all affected
What are some of the concerns around genetic testing for cancer in children?
Testing children – benefits and harms must always be considered. Suggestions are that testing should be considered with great caution and delayed until the child is able to decide for themselves. This may be influenced by the type of cancer, typical age of onset and management options.
What are the elements of a cancer risk assessment?
Should be an interdisciplinary process
Medical history
Family history – create a family tree, identify patterns, explore maternal and paternal paths
Ethnicity
Patient history- environmental/chemical exposure, lifestyle behaviours, previous history of cancer/pre-cancer, previous biopsies, pathology reports
Physical exam
Screening activities
Counselling – education, health promotion, informed consent, support
What are some important questions regarding self genetic testing?
Some questions: What is their intention? Are they accurate and reliable? Who regulates them? Privacy laws around genetic information? Can this data be used/sold for research? Lead to discrimination?
What percentage of colorectal cancers are related to genetic factors?
Approx. 5-6%
What are two autosomal dominant syndromes that are genetically predisposing to colorecal cancer?
Familial adenomatous polyposis – approx 1% of CRC
Hereditary nonpolyposis colorectal cancer (Lynch syndrome) – approx 5% of CRC
Both are autosomal dominant syndromes.
