Review for 10.1186/s12876-016-0503-7 (2016)

Reviewer ’s report  
Title : Associations between polymorphisms in folate -metabolizing genes and pancreatic c ancer 
risk in Japanese subjects  
 
Version:  0 Date:  18 Feb 2016  
 
Reviewer:  Harkirat  Singh  
 
Reviewer's report:  
This is a case control study evaluating the associati on between folate metabolizing gene 
polymorphisms and pancreatic cancer in japanese patients. Authors have done a good job.  
 
Title: Appropriate  
Introduction/Background: Adequate length, explains the reason for the study clearly and explains 
the hypothesis . One thing that can be clarified is the results of both the japanese studies on this 
topic (Suzuki et al,Ohnami et al)  instead of clubbing it with the studies in other populations (Li 
et al in non hispanic US whites, wang et al in chinese and Matsubayash i et al in americans). 
Reason being genetic polymorphisms and phenotypes and vary in different ethnic, geographic 
and racial populations.  
 
Methods: There is no description of how the sample size was determined for the main 
hypothesis. Please explain about calculation of sample size in this section. Also explain about the 
sample size needed to find interactions/effect modifications (smoking, alcohol and dietary folate 
intake) with the exposure in question (gene polymorphism) and effect (pancreatic cancer)  
 
Results:  OK 
Discussion:  
In the first paragraph, please discuss both the previous japanese studies. Please clearly mention 
that your results for MTHFR polymorphisms are not different from previous two Japanese 
studies for gentotype alone. In the 2nd paragrap h, it is stated that your results of null findings on 
association between MTHFR genotypes and panc cancer can be from difference observed in 
minor allele frequencies among ethnic populations. Are you comparing it with non -japanese 
studies or the japanese s tudy with positive association for MTRR polymorphism (Ohnami et al)? 
How is the ethnicity of your population different from other japanese studies? What reasons can 
you give for the different results from study by Ohnami et al?  
 
Overall the message from y our results is that there is no association noted for genetic 
polymorphisms alone and there is not enough data for calculating effect modification due to 
alcohol,smoking or folate intake (gene -environment interaction). I would make this more clear in 
the e nding of your discussion.  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
Yes 
Does the work include the n ecessary controls?  
If not, please specify which controls are required in your comments to the authors.  
Yes 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
Yes 
Are you able to assess any s tatistics in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your comments to the editors.  
I am able to assess the statisti cs 
Quality of written English  
Please indicate the quality of language in the manuscript:  
Acceptable  
Declaration of competing interests  
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