Characterization of a Compound Heterozygous SLC2A9 Mutation That Causes Hypouricemia

Round 1

Reviewer 1 Report

Dear Authors ! You have a quality manuscript. I enjoyed reading it. 

Author Response

Thanks for your nice comments for this paper. We revised manuscript following your comment. 

Sungkweon Cho.

Reviewer 2 Report

Cho et al. investigated the genetic cause of hypouricemia based on their previously reported exome study. Interestingly, the authors found that major of hypouricemia can be related to two SLC22A12 variants (SLC2A9a and SLCA9b) of codons p.Met155Val and p.Met126Val. Next, the authors have performed a molecular dynamic study which revealed that p.Met155Val causes  a defect on the geometry of outward open which prevents uric acid transport. Finally, the authors showed that variant p.Met155Val does not affect on the expression of SLC2A9 mRNA, however, significantly impaired the uric acid transport in cells. Overall, this is an interesting study which unravel a novel mutation as a cause for hypouricemia. Although the authors results and conclusion are based on a limited no of samples, I think the significance of obtained results support their results. The study is well-designed and performed. I would recommend the publications of this study after addressing the following concerns:

- the abstract is poorly written and contains many grammatical mistakes- please modify it

- the introduction is very short and does not really cover the state of the art around the topic.. please modify it and cite the most recent and relevant studies.

- overall the manuscript needs a moderate English editing

- regarding the MD study, the authors should provide a closer overview about the binding affinity of the uric acid inside the membranes? Are there any kind of inteactions which stabilize the membrane deformation under mutation conditions?

- again since the authors based on MD for their hypothesis, it would be beneficial if the authors show how deep would be the interaction (amino acids essential) and compare to non-mutated case.. that would be applied for fig3 and 2.

- the authors did not submit the supplementary data, so it is not possible to check the figures and tables

Author Response

Cho et al. investigated the genetic cause of hypouricemia based on their previously reported exome study. Interestingly, the authors found that major of hypouricemia can be related to two SLC22A12 variants (SLC2A9a and SLCA9b) of codons p.Met155Val and p.Met126Val. Next, the authors have performed a molecular dynamic study which revealed that p.Met155Val causes  a defect on the geometry of outward open which prevents uric acid transport. Finally, the authors showed that variant p.Met155Val does not affect on the expression of SLC2A9 mRNA, however, significantly impaired the uric acid transport in cells. Overall, this is an interesting study which unravel a novel mutation as a cause for hypouricemia. Although the authors results and conclusion are based on a limited no of samples, I think the significance of obtained results support their results. The study is well-designed and performed. I would recommend the publications of this study after addressing the following concerns:

- the abstract is poorly written and contains many grammatical mistakes- please modify it

-> We modified the abstract according to your suggestion. Abstract is re-written.

- the introduction is very short and does not really cover the state of the art around the topic.. please modify it and cite the most recent and relevant studies.

->We modified the introduction and cited the most recent and relevant studies.  

- overall the manuscript needs a moderate English editing

-> We modified the manuscript according to your suggestion.

- regarding the MD study, the authors should provide a closer overview about the binding affinity of the uric acid inside the membranes? Are there any kind of inteactions which stabilize the membrane deformation under mutation conditions

-> The overview of the site will be provided in the future study with better description. We will descibe the this unique phenomenon in the following paper.

- again since the authors based on MD for their hypothesis, it would be beneficial if the authors show how deep would be the interaction (amino acids essential) and compare to non-mutated case.. that would be applied for fig3 and 2.

-> Thanks for your kind comment. We also validated the result  of different uric acid transport using xenopus oocyte. We can provide this information in the next round of revision if it is necessary.

- the authors did not submit the supplementary data, so it is not possible to check the figures and tables

-> Supplementary material was submitted initially. I uploaded supplementary as one document.

Reviewer 3 Report

This manuscript tackles hypouricemia. Although hypouricemia is a rare condition usually with subclinical course of disease, it may in some cases evoke acute renal injury (previously called acute renal failure).

In most patients hypouricemia was explained by SLC22A12 gene variants. In this artricle the Authors report, that SLC2A9 gene mutation was prasent in patients with previousley unexplained hypouricemia. The article with a sound scientific background brings interesting novel insight into pathology of a rare condition. The new information may help to optimize the therapy in mutation carriers when they become symptomatic.

Author Response

Thanks for your nice comments for this paper. We revised manuscript following other reviewer's comment. 

Sungkweon Cho.

Round 2

Reviewer 2 Report

Indeed, I'm so frustrated that the authors did not put any effort to modify their manuscript. The authors have NOT satisfied the concerns mentioned in the first report. It's wasting time to write again the same concerns that I have mentioned in the first round.

1- - the abstract is poorly written and contains many grammatical mistakes- please modify it

Authors Reply-> We modified the abstract according to your suggestion. Abstract is re-written.

However, the new abstract is the following:

Abstract: A single paragraph of about 200 words maximum. For research articles, abstracts should give a pertinent overview of the work. We strongly encourage authors to use the following style of structured abstracts, but without headings: (1) Background: Place the question addressed in a broad context and highlight the purpose of the study; (2) Methods: briefly describe the main methods or treatments applied; (3) Results: summarize the article's main findings; (4) Conclusions: indicate the main conclusions or interpretations. The abstract should be an objective representation of the article and it must not contain results that are not presented and substantiated in the main text and should not exaggerate the main conclusions.

2- the introduction is very short and does not really cover the state of the art around the topic.. please modify it and cite the most recent and relevant studies.

Authors Reply->We modified the introduction and cited the most recent and relevant studies. 

R Comment: The introduction has NOT improved. The intro is based on studies reported 10ys ago or even longer. The style of citations does not follow journal style. The changes MUST be highlighted in color so it is easier to follow and check.

3- overall the manuscript needs a moderate English editing

Authors Reply-> We modified the manuscript according to your suggestion.

R Comment:I do not see any change/editing has been performed. If the authors have a language problem, they can submit their MS to MDPI service to be edited and proof-reading.

4- - regarding the MD study, the authors should provide a closer overview about the binding affinity of the uric acid inside the membranes? Are there any kind of inteactions which stabilize the membrane deformation under mutation conditions

Authors Reply->The overview of the site will be provided in the future study with better description. We will descibe the this unique phenomenon in the following paper.

R Comment: the presented paper is mainly based on this  phenomenon. Therefore, the authors should presented and cover this point.

5- - again since the authors based on MD for their hypothesis, it would be beneficial if the authors show how deep would be the interaction (amino acids essential) and compare to non-mutated case.. that would be applied for fig3 and 2.

Authors Reply->Thanks for your kind comment. We also validated the result of different uric acid transport using xenopus oocyte. We can provide this information in the next round of revision if it is necessary.

R Comment: I think, it was clear from my first report that this information should be beneficial and valuable to be included in this MS. Therefore, the authors should include and cover this point.

Author Response

Dear honorable reviewer, 

I appreciate your comment and I hope you to understand that the editor only gave us for 3 days for the minor revision for the second round. 

1. I modified the abstract following your comment. Please check the revised the manuscript. This journal already formatted their own style. English of this paper was revised twice by native speakers; Cheryl Winkler (my mentor) and Victor David.  

2. The reference style was changed following MDPI style. The introduction was improved citing new article from PNAS and etc.

3. This version was done several times of proofreading in our group. 

4. The mutation was proven by urate transport activity study. The main result is figure 4. I wish you understand that the further GLUT9 MD study including all known variants will be done in the separate paper.

5. Quantum mechanic approach will be covered in our next paper. I hope you would understand this point. 

Overall, the editorial office only gave us for 3 day for the minor revision and Raul (who've worked on MD study) in our team is sick for the fracture of his leg. We did our best for the second round. If you have any concern, I will cover it at the third round. 

Sincerely, 

Sung Kweon Cho 

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

The author have modified their manuscript.