Lecture 11- Non-clinical uses of genetic testing Flashcards
What are some of the non-clinical uses of genetic testing?
- Clinical and non-clinical purposes for genetic testing
- Risks of monogenic or complex diseases
- Pharmacogenetics /pharmacogenomics
- What else?
- Physical characteristics
- Nutrition,genes and health
- Sporting success
- Identity/paternitytesting
- Ancestry tracking
What is DTC (direct-to-consumer) genetic testing?
- Genetic tests that are marketed directly to consumers via television, print advertisements, or the Internet tests range from the obvious (eye colour) to the dubious (athletic ability), to the serious (cancer)
- clinical and personal utility variable
- This form of testing, also known as at-home genetic testing, provides access to a person’s genetic information without necessarily involving a doctor or insurance company in the process
What are the benefits of DTC genetic testing?
- Convenient availability /accessibility
- Competitive prices
- Consumer autonomy
- Freedom to choose which test(s)
- Control over privacy of results
- Ability to plan for the future
• Networking
- can just send a saliva sample, easy to do from home
- prices low since it is competitive
- idea that it will empower individuals
- info to help you decide how to live your life dependent on your results
Who has provided DTC genetic testing?
- More than 50 companies
– a fluctuating market
- Most companies have been based in the USA, but could be easily set up in other countries (some with less regulation – ‘spit’ travels!)
- Typically use SNP genotyping (genome scan)
– mostly based on GWAS data, others are pathogenic variants
- almost always just a saliva test, sometimes blood but unusual
- mostly use genotyping, do genome scan
- SNP genotyping, they also use data from genome wide data -
What is the predictive ability of DTC genetic testing?
- the predictive ability from GWAS vs genome sequencing
- once have more complex disease, hard to get the susceptibility, heritability etc. risks well
What is the clinical and personal utility of DTC genetic testing?
- Analytical validity is usually high
- Clinical validity is unclear
- Clinical and personal utility is unclear
- Awareness of these factors within the scientific/general communities
- Interpretation and application of results based on their clinical/personal utility
- interpretation and clinical validity is not great with genome wide association
What is nutritional genomics?
- Nutritional genomics – relationship between genes, nutrition and health
- Nutrigenetics
- Variations in an individual’s genotype (SNPs) that contributes to their response to diet (and health)
- eg individuals responding differently to the same diet because they have different levels of, for example, certain biological markers such as serum cholesterol and blood pressure due to genetic variation
- Nutrigenomics
- Role of nutrients (diet) in gene expression
- eg polyunsaturated fatty acids (omega-3) modulate expression of multiple genes
- Role of epigenetics
- there is a relationship between genes nutrition
- but to what extend does that really affect you - nutrigenomics= how food affects genes and their expression
What is the genetic component in blood pressure? (nutrigenetics)
- Essential hypertension – causative factors:
- genetics (many genes)
- nutrition (sodium chloride, low potassium, low calcium, low omega-3 fatty acids)
- other environmental (obesity, alcohol, stress, physical activity)
- Genetic variation probably responsible for salt sensitivity, therefore for some people (with relevant genetic variants) reducing salt intake won’t necessarily reduce blood pressure
What is the effect of Omega 3 fatty acids on genes?
- Omega-3 polyunsaturated fatty acids (eg in fish oils) modulate gene expression of many genes known to be involved in inflammatory pathways (ie have anti-inflammatory effects)
- Prostaglandin metabolism
- Decrease triglycerides
- Decreasecholesterol
- Cytokine production
- Anti-thromboticeffects
What is the connection between genes and sport?
- Strong genetic basis for human physical performance and elite athlete status
- Endurance, power, response to training
- Other factors that determine success include:
- Epigenetics
- Environmental influences, such as
- Training
- Motivation
- Nutrition
- Advances in equipment, etc
- genetic studies often not conclusive and at times contradictory
- small numbers, heterogeneous populations (gender, ethnicity, sport discipline)
- the circled ones are the ones that we need to know
- ACE I for endurance
- ACE D, ACTN3 for powersport
What are the genes for endurance?
Endurance:
• ACE II genotype
- angiotensin converting enzyme
- regulates blood pressure
- I (insertion in intron) allele (lower ACE activity)
- D (deletion in intron) allele (higher ACE activity)
What are the genes for power?
- ACE DD genotype
• ACTN3 RR genotype
- a-actinin 3: expressed in skeletal muscle, fast twitch fibres
- R allele (gene expressed)
- X allele (null - gene not expressed)
- ACTN3 XX & ACTN3 XR
– very common polymorphisms; deficiency associated with efficient aerobic metabolism
Are the genes for particular type of sport really that clear and cut?
-25% of the population have the ACE II genotype and not all are endurance athletes!, it is common in athletes but not predictive -ACTN3 RR genotype, the “speed gene”, codes for alpha-actinin 3, showed that it is much more common in power athletes, if you have the allele R (expressed and X not expressed) -again about 25% of the population have the RR, about 50% have heteroyzgous, and the null allele is also very common (selective pressure?) -some sporting clubs now test their players (AFL, rugby) -but we cannot predict who is going to be an elite athlete! -but some claim it is so clearn and cut, this company markets it as that you can pick the sport for your child so they maximise their chances at being an athlete
How is DNA profiling useful for identity?
- Identify potential suspects whose DNA may match evidence left at crime scenes - Exonerate persons wrongly accused of crimes
- Identify crime and catastrophe victims
- Establish paternity and other family relationships
- Match organ donors with recipients in transplant programs
- Identify endangered and protected species as an aid to wildlife officials (could be used for prosecuting poachers)
- Detect bacteria and other organisms that may pollute air, water, soil, and food
- Determine pedigree for seed or livestock breeds
- Authenticate consumables such as caviar and wine
How is genetic testing used for ancestry tracking?
- Tracking individual genetic lineages
- mitochondrial DNA (maternal line) andY-chromosome DNA (paternal line)
- Tracking personal ancestry
- chromosome painting, can see which parts of your chromosomes are more associated with one ethnic group or another
