Question | Answer |
Epidemiology | The study of agents affecting health and illness in populations and the foundation of public health and preventative medicine |
Attributable fraction | That proportion of a disease that could be eliminated by removing the risk factor (allelic variant or environmental exposure for example) from the population. |
Odds Ratio | The odds of a disease occurring in one group compared to the odds of it occurring in a comparison group. Most often applied in case-control studies. |
Relative Risk | Probability of a disease occurring in an exposed compared to an unexposed group. Most often used in controlled trials and cohort studies. |
Genome Wide Association Study | A comprehensive study of a set of SNPs across the entire genome to determine association with a disease and with no prior hypothesis on which SNP/gene might be associated |
Twin design | compares the similarity of identical twins who share 100% of their genes, to that of dizygotic or fraternal twins, who share only 50% of their genes. |
Twin studies help researchers understand | the role of genetic effects, and the effects of shared and unique environment effects. |
segregation analysis | The determination of the number of progeny that have inherited distinct and mutually exclusive phenotypes. compare all possible models to observed data |
H squared | The proportion of the total variance for a trait caused by genes H is approx=1 with height |
odds ratio | the ratio of the odds of an event occurring in one group compared to the odds of it occurring in another group |
The odds ratio is used for | case-control studies and retrospective studies AND for the approximation the relative risk for small probabilities |
Relative risk | probability of Dz occurring in exposed group compared to unexposed. 2) Used in randomized controlled trials and cohort studies |
Genome Wide association | For identification of common variants in common/complex traits 2) involves rapidly scanning markers across the complete sets of DNA, or genomes, of many people to find genetic variations associated with a particular disease. |
what is the problem with genome wide association | problem is multiple comparison AND Billions of data points |
How can Genome wide association be useful | researchers can use the information to develop better strategies to detect, treat and prevent the disease. also pharmacogenetics and personalized medicine ex) asthma, cancer, diabetes |
model for the implementation of related genetic testing in the market | variability in dosing of warfarin attributed to genetic variants. The incorporation of genetic testing for these variants (i.e. those at risk) is the model |
SNPS and Prostate Cancer for example_Odds ratios based on | number of SNP risk factors and family history positive |
Microbiome | is that collection of microbes in/on you |
Metagenome | is the genomic content of you |
Cohort study | often undertaken to obtain evidence to try to refute the existence of a suspected association between cause and disease |
A cohort is | a group of people who share a common characteristic or experience within a defined period |
The 2X2 table | used to determine significance of risk and its magnitude (chi squared) by recording and analysing the relationship between two or more variables |
Relative risk and Odds ratios are the same when | the disease is rare in a population |
clinical validity of a test | important to consider in cohorts to determine if a test should become a clinical tool; describes both the positive and negative value for a test |
Positive predictive value | Fraction of people with risk variant who will develop disease |
Negative predictive value | Fraction of people without risk variant who will not develop disease |
PPV is high for | rare Mendelian disorders like cystic fibrosis |
PPV is low for | complex traits like diabetes |
An allelic variant with a small RR/OR ratio | may have substantial public health impact if allele is common. attributable fraction measures the impact (smoking cessation programs driven by estimates of their effect on disease prevalence) |
Identifies many alleles associated with small (OR 1.1-1.5) risks for common complex traits | Genome Wide association studies |
environmental variables may be well defined for some.... | disorders and have similar numerical risk profiles (OR) |
By combining multiple alleles each with additive risk | individual risk profiles can be developed so that a small number of persons can be identified as "at risk" |
Direct to consumer testing and genetics | commercial entities made tests available for common alleles associated with predisposition to common traits that include a genetic risk 2) use DNA chips 3) test for SNP variants |