Review for 10.1186/s12876-017-0613-x (2017)

Reviewer ’s report  
 
Title: Vitamin D -related gene polymorphism predict treatment response to pegylated interferon -
based therapy in Thai chronic hepatitis C patients  
 
Version: 0 Date: 09 Feb 2017  
 
Reviewer: C.-Thomas Bock  
 
Reviewer's report:  
 
Dr Thanapirom and colleagues have presented an interesting observational study in which they 
aimed to determine whether polymorphisms in genes of vitamin D were associated with 
treatment response to IFN/RBV in chronic HCV infected Thai patients. The author s enrolled 623 
Thai patients from 2 university hospitals who were treated with Peg -IFN/RBV for chronic HCV. 
The colleagues analysed known gene polymorphisms of the vitamin D synthetic pathway and 
determined the HCV genotype. As a result of their study the authors concluded that in Thai 
patients with HCV genotype 1 infection the DHCR/ polymorphism were independent predictors 
of improved IFN/RBV treatment outcome and thus could be useful as a predictive marker for 
treatment response.  
Overall, the study is we ll performed and concise in its content showing convincing data. 
However, I have minor comments which should be addressed.  
 
Comments  
1. Because of the importance of vitamin D levels in HCV infected persons; did the colleagues 
determine vitamin D levels of the patients of the study?  
2. Concerning the IFN/RBV therapy, there is no information in terms of duration of treatment 
in the patient groups.  
3. Table 1. I don't understand the last characteristics PEG -IFN-a 2a? Please explain this value.  
4. As a suggest ion for the discussion section, there are very recent and important reports on 
vitamin D and HCV infection contributing to the findings of this study (Wu et al. J Hum 
Genet, 2016,61:129 -135; Hung et al, J Formos Med Assoc 2016; 115:278 -283, and Loftfield 
et al 2016;11:e0166036). Therefore I suggest discussing these studies in the context of the 
results of the colleagues.  
 
 
 
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 necessary controls?  
If not, please specify which controls are required in your comments to the auth ors. 
 
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 statistics 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 recommend additional statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscr ipt: 
 
Acceptable  
 
Declaration of competing interests  
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3. Do you hold or are you currently applying for any patents relating to the content of the  
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5. Do you have any other financial competing interests?  
 
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