I am working on a research about association between hypertension and only one SNP. After statistical study, i found there is No association between genotype and phenotype. how can i explain and discuss that?
Thanks
It is always more difficult to discuss "what is not there" than what is there. Is it possible that the research design itself and/or limitations to the study may have been a factor? If there is any explanation to your findings then I would discuss that even if it is only conjecture. I have always felt that the "negative" findings are just as important as the "positive" findings. Good luck!!
Do yu have calculate the statistic power? Maybe the negative finding is due to the low power. Why you study only one SNP? It is functional or well-replicated? If it is well-replicated in many study, the possible reason for your negative findngs may be due to the differences of sample characteristics, such as ethinicity, clinical symptoms severity, gender, or others. Hope helpful.
You need to show with reasonably high power (e.g. 95%) that the magnitude of the association is less than the smallest amount that could be of clinical importance. Do this by putting an appropriate confidence interval on the magnitude of the association. See Proving the null hypothesis in clinical trials by Blackwelder WC - Controlled Clinical Trials, 1982
Volume: 3:345-353.
It is always harder to report a non-significant association. As the other investigators pointed out, it is necessary to calculate the statistical power based on the reported odds ratio and the allele frequencies from your sample set. Quanto is a reasonable simple software to use http://biostats.usc.edu/software. The other factors are whether your dataset is comparable to the reported studies in terms of ethnicity, diagnosis, clinical phenotyping using the same standard and age/gender. If you are using PCR-based Sanger sequencing or TaqMan-based DNA genotyping, no questions will be related with your experimental method. Otherwise, you may want to make sure your genotyping works in the situation that you have reasonable statistical power to detect the reported association. Best luck to your study.
The most simple explanation may be that there is no true association between your SNP and the phenotype. If you have good evidences to think that the gene or the locus under investigation is involved in the modulation of hypertension, maybe your SNP is not in linkage diseiquilibrium with the "functionnal (s)" genetic variants that would be associated with hypmertension.
The whole picture should be looked at before going for a response. It is a difficult topic, it is still a puzzle.
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