compared inn the study inly, howver toain between individuals in human populatio
ID: 189693 • Letter: C
Question
compared inn the study inly, howver toain between individuals in human populations. In compared in pairs of monozygotic (MZ) and dizygotic (DZ) twins tegearch Study 1 There is wide variation in the response to pain between similarity. In the study indicated here, pressure pain thres pain sensitivity have been reported to show had been reared together as children by their natural parents objective of the study was to determine the relative contn factors in determining pain perception. and dizygotic (DZ) twins. Female-female twin pairs who were used in this study. The contribution of genetic and environmental ssure pain thresholds were assessed using a variable pressure do re undertaken at the forehead with the patient seated lorimeter. The measurements we The dolorimeter was placed perpendicular to the forehead and the pressure was rase 2 kg/cm2/s. When the subject said yes,' the pressure was sto Co-twin responses were assessed without the other twin present. and the dolorimeter i MZ twins Scatterplot of PPT in MZ DZ twins and DZ twins. The labels 'Twin 16 1' and Twin 2 are allocated arbitrarily (i.e. there was no particular reason for placing arn individual on the x or axis). 12 10 10 PPT Twin 1 PPT Twin 1 kge A. Compare/contrast the pressure pain threshold findings shown for the mon B. Based on what you see in these scatterplots, how do you interpret the level of genetic C. No matter what you concluded in part B, if you now wanted ozygotic and dizygotic twins. environmental contributions to the observed phenotype of pain sensitivity? Explain. specifically a "genetic-environmental" component (VoE) in this pain ph and to know if there was you go about determining this? Explain.Explanation / Answer
A. Similarities between the plots:
a) The pressure pain threshold findings shown for the monozygotic and dizygotic twins show a positive relationship (strong correlation) between the twins.
b) Both the graphs have an interquartile range of 2-4kg/cm2.
Contrast between the plots:
a) The PPT plot of mono-zygotic twins seems to be strongly correlated than the PPT plot of di-zygotic twins.
b) Outliers can be observed in the plot of dizygotic twins. This could be due to human error, instrumental error, etc., But in this case, it could be the result of a flaw in the assumed theory or natural deviations in populations.
2. In twin studies, the environmental influence is considered equal. So it can be hypothesized that a concordance in monozygotic twins represents a genetic influence. If the correlation is stronger in monozygotic twins than dizygotic twins, the hypothesis is supported. In ths case, the genetic contribution seems equal. Shared environment influences more, according to research.
3. Other approaches include:
a) Transmission disequilibrium test can be done to test for the presence genetic linkage (tendency of DNA sequences which are close together on a chromosome) between a genetic marker and a trait.
b) Allele-sharing method can be used to analyze phenotypically well-characterized families with DNA available from at least two affected family members.
c) Case-control study can be performed by collecting phenotype data and DNA samples from patients and unrelated controls followed by genotyping of the polymorphisms.
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