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: 28 Jan 2020  
 
Reviewer: Praveen Kumar  
 
Reviewer's report:  
 
Please include all comments for the authors in this bo x rather than uploading your report as 
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The study by Jessica Seeßle is an interesting study and well -written. It needs revision. I have 
the  following major and minor queries.  
 
 
 
Major suggestion:  
 
Why did the author not check for normality of data and a pply appropriate statistics 
(parametric/non -parametric statistical test and corresponding descriptive statistics)  
 
Did the author go for Welch correction, as they had uneven sample size?  
 
The authors resorted to Chisquare test alone. Was the expectancy count  in contingency table 
of all categorical variables &gt;5? If not, was Fisher exact test explored.?  
 
What methodology was used for the determination of PNPLA3 polymorphism 
(rs738409/I148M). How is wildtype (CC), heterozygous (CG) and homozygous (GG) 
defined?  
 
The study consists of two parts. Evaluation of lipid profile in HH and evaluation of  PNPLA3 
polymorphism in HH. The weightage given to the  PNPLA3 polymorphism in the discussion 
and in the overall article needs to be increased. Further explanation or pos sible molecular 
hypothesis on the reason behind the non -differing lipid profile  between the  PNPLA3 
polymorphism needs to be mentioned.  
 
 
 
 
 
 
 
 
Minor suggestion:  
 
The author writes "decreased high -density lipoprotein (HDL), altered composition of very -
low dens ity lipoprotein (VLDL) - and HDL - particles"  
 
HDL is mentioned two times in this sentence.  
The author writes " Iron excess induces distinct changes in the serum concentrations of 
phosphatidylcholine (PC) subsets in diabetes mellitus type 2."  
 
What does the su bsets refer to over here?  
 
The author writes "Hence, iron has effects on hepatocellular metabolism 63 of phospholipids 
and lipoproteins, and on unsaturation of fatty acids in experimental settings."  
 
The author can mention this sentence after providing the clinical evidence (which they have 
provided in the paragraph after experimental settings). And you can write as "Hence, iron has 
effects on hepatocellular metabolism 63 of phospholipids and lipoprote ins, and on 
unsaturation of fatty acids in experimental and clinical settings."  
 
The author writes "Ultrasound and evaluation for liver fibrosis using noninvasive method 
(Fibroscan) was performed by experienced medical doctors to evaluate hepatic steatosis 
graduated as normal, mild, moderate or severe."  
 
What was the duration of experience?  
 
What guidelines was taken for the grading into normal, mild, moderate or severe.  
 
The author writes "The two groups were significantly different 116 in serum iron contents  
(transferrin 2.1 vs. 1.8 g/l, p=0.0001, transferrin saturation 26.0% vs. 70.1%, 117 
p&lt;0.0001, iron 13.5 µmol/l vs. 31.8 µmol/l, p &lt;0.0001, ferritin 155.0 µ/l vs. 636.7 µ/l, 
p=0.03)."  
 
What does the two groups stands for? Need to mention what value sta nd for HH and what 
values stand for the control. The readers cannot presume things.  
 
The author writes "In addition to serum neutral lipids and lipoproteins, we also determined 
serum contents of polar lipids (phospho - and sphingolipids) in 53 subjects with  HH. The 
levels of serum phosphatidylcholine (PC), lysophosphatidylcholine (LPC), 
phosphatidylinositol (PI), phosphatidylserine (PS),  phosphatidylethanolamine (PE), 
lysophosphatidylethanolamine (LPE), and sphingomyelin (SM) in HH patients were 
compared wi th those of healthy control group"  
 
This sentence should come in the material and methods section rather than the results  
 
The author writes "In our cohort, triglycerides were obviously higher in HH, but significance 
was narrowly not 159 reached."  
 
In stati stical science, there is no word for narrowly not reached. It can either be significant or 
not-significant. These kinds of description does not look good.  
Discussion needs to be bit elaborated in the context of  PNPLA3 polymorphism. What are the 
findings of other studies in which PNPLA3 have been explored and how other study results 
are corroborating with this study results.?  
 
It is not mentioned in table 1 and table 2 - what does the data stand for ? and what were the 
statistics applied for computing the p value?  
 
 
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:  
 
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3. Do you hold or are you currently applying for any patents relating to the content of 
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5. Do you have any other financial competing interests?  
 
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