Review for 10.1186/s12876-020-01282-3 (2020)

Reviewer’s report  
 
Title: Plasma Lipidome, PNPLA3 polymorphism and hepatic steatosis in hereditary 
hemochromatosis  
 
Version: 0 Date: 24 Jan 2020  
 
Reviewer: Vincent Wong  
 
Reviewer's report:  
 
In a cross -sectional study, Seeßle and colleagues performed serum lipidomic analysis and 
PNPLA3 gene polymorphism testing in 54 patients with hereditary hemochromatosis and 20 
healthy controls. They found that patients with hereditary hemochromatosis had r educed 
serum phosphatidylcholine and increased phosphtidylethanolamine. The PNPLA3 gene 
polymorphism, a well -known genetic determinant of hepatic steatosis, did not affect the 
histological features as well as iron and lipid parameters in patients with here ditary 
hemochromatosis. Although this is a rather small study that is probably underpowered for 
lipidomic and genetic analysis, the findings are novel and interesting.  
 
Major points:  
1. In a few places, the authors state that triglycerides were obviously h igher in hereditary 
hemochromatosis but the difference did not reach statistical significance. In comparing 
continuous variables, one should consider not only the means but also the dispersion of 
values. If the difference is not significant, please avoid m aking claims casually.  
2. The authors should describe how the diagnosis of hereditary hemochromatosis was made.  
3. Did any patients take lipid lowering drugs? This might affect the lipidomic analysis.  
4. Please also describe the treatment for hereditary  hemochromatosis and whether it affected 
the lipid indices.  
 
Minor points:  
5. Please write PNPLA3 in italic form whenever you are referring to the gene.  
6. The authors do not need to spell hereditary hemochromatosis in full again (e.g. page 5) 
after defin ing the abbreviation of HH earlier.  
7. Page 7, first paragraph: It should be "higher serum PE" rather than "serum higher PE".  
8. Page 7, second paragraph: It should be "still remains unclear" rather than "remains still 
unclear".  
9. Page 7, second paragraph: There is a typo "secretion8".  
10. Page 8, last paragraph: It is more common to write "type 2 diabetes mellitus" than 
"diabetes mellitus type 2".  
11. Table 1: The title should read as "Clinical characteristics" instead of "Dem ographics". 
The content is broader than "demographics" alone.  
12. Tables 1 and 3:  
- People usually write "hepatic steatosis" instead of "steatosis hepatis".  
- Tables 1 and 3: For hepatic steatosis, it would be more logical to list in the sequence of 
"none , mild, moderate and severe" rather than "mild, moderate, severe and none". It would be 
better to have a global chi -square test and one P value for this parameter. It is not meaningful 
to compare each steatosis grade separately.  
13. Table 2: Some paramete rs do not appear normally distributed, as evidenced by large 
standard deviations with reference to the mean values. Those parameters should be reported 
as median (interquartile range) and compared using non -parametric tests.  
 
Are the methods appropriate an d 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 authors.  
 
Yes 
 
Are the conclusions drawn a dequately 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 am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscr ipt: 
 
Acceptable  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from 
an organisation that may  in any way gain or lose financially from the publication of 
this manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose  
financially from the publication of this manuscript, either n ow or in the future?  
 
3. Do you hold or are you currently applying for any patents relating to the content of 
the manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds  or has applied for patents relating t o the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
If you can answer no to all of the above, write 'I declare that I have no competing int erests' 
below.  If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests.  
 
I agree to the open peer review policy of the journal. I understand that my name will be 
included  on my report to the authors and, if the m anuscript is accepted for publication, my 
named report  including any attachments I upload will be posted on the website along with the 
authors'  responses. I agree for my report to be made available under an Open Access Creative 
Commons  CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understand that 
any comments  which I do not wish to be included in my named report can be included as 
confidential comments  to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal