Gene variations and sweet taste sensitivity in Zambian adults with and without type 2 diabetes mellitus

Tuku Mwakyoma; Catherine Anna-Marie Graham; Benson M. Hamooya; Lweendo Muchaili; Memory Ngosa; Joreen P. Povia; Leta Pilic; Sepiso K. Masenga

doi:10.1371/journal.pone.0328172

Peer Review History

Original SubmissionNovember 14, 2024
Decision Letter - Md. Asaduzzaman, Editor Dear Dr. Mwakyoma, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Jan 15 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols . We look forward to receiving your revised manuscript. Kind regards, Academic Editor PLOS ONE Journal Requirements: When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. We note you have included a table to which you do not refer in the text of your manuscript. Please ensure that you refer to Table 2 in your text; if accepted, production will need this reference to link the reader to the Table. 3. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? Reviewer #1: Partly Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #1: Yes Reviewer #2: Yes ****** Reviewer #1: The manuscript has low quality. It did not address any specific gap they intended to fill. Furthermore, it does not add anything to the subject area compared with other published Material. Therefore, any comments regarding the methodology are equivocal. In addition, the discussion was inappropriate. This manuscript does not fulfill the standards established for the journal to be considered for publication. Reviewer #2: The Manuscript sounds ok according to the number of participants. I think sample size is small. But its ok but you should add more case studies to prove the data and add more references and improve little bit your english. ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #1: Yes: Shooka Mohammadi Reviewer #2: Yes: Sammra Maqsood ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step. Attachments Attachment Submitted filename: PONE-D-24-49147.pdf https://doi.org/10.1371/journal.pone.0328172.r001
Revision 1
10 Mar 2025 Author Response Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf Response: Formatted as advised 2. We note you have included a table to which you do not refer in the text of your manuscript. Please ensure that you refer to Table 2 in your text; if accepted, production will need this reference to link the reader to the Table. Response: The table has been cited 3. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. Response: Captions have been added for supporting information files Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Partly Reviewer #2: Yes Response: we have made adjustments to ensure that the manuscript support the conclusions ________________________________________ 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes Response: Thank you ________________________________________ 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes Response: Thank you ________________________________________ 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes Response: Thank you ________________________________________ 5. Review Comments to the Author Reviewer #1: The manuscript has low quality. It did not address any specific gap they intended to fill. Furthermore, it does not add anything to the subject area compared with other published Material. Therefore, any comments regarding the methodology are equivocal. In addition, the discussion was inappropriate. This manuscript does not fulfill the standards established for the journal to be considered for publication. Response: We appreciate the reviewers comment. We have added more information to address the specific gap and have clearly written out the main goal of the study. Our study is unique in this population and we present novel results. One main reason for the apparent discrepancy with published material is because the black African population is genetically different so much that there are variations in SNPs. We think that our study will provide good baseline data for future studies that build on this field of study. Further, there are few studies which have investigated taste sensitivity and measured these genetic SNPs in African populations. We did a thorough search of literature as reported in the introduction and discussion to this effect and found no specific study. We went ahead to add more SNPs to provide more relevance to the study. The limitation here is that the SNPs that may be associated with taste sensitivity in Caucasian populations where these studies are conducted may not necessarily be similar to our population. Measuring a wide ray of SNPs would be better in identifying SNPs common to African populations but the cost implications are prohibiting and beyond the scope of our study. Reviewer #2: The Manuscript sounds ok according to the number of participants. I think sample size is small. But its ok but you should add more case studies to prove the data and add more references and improve little bit your English. Response: We want to thank the reviewer for the suggestions. We have now added more single nucleotide polymorphisms to our data to enrich the manuscript and provided more clearer aims. We have also made editions to the grammar throughout to improve the manuscript. In addition, refer to our response to reviewer 1 for additional changes we have made to improve the manuscript ________________________________________ Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0328172.r002
Decision Letter - Md. Asaduzzaman, Editor Dear Dr. Mwakyoma, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. ============================== ACADEMIC EDITOR: Please insert comments here and delete this placeholder text when finished. Indicate which changes you require for acceptance versus which changes you recommend Address any conflicts between the reviews so that it's clear which advice the authors should follow Provide specific feedback from your evaluation of the manuscript publication criteria and not, for example, on novelty or perceived impact. For Lab, Study and Registered Report Protocols: These article types are not expected to include results but may include pilot data. ============================== Please submit your revised manuscript by May 12 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols . We look forward to receiving your revised manuscript. Kind regards, Academic Editor PLOS ONE Journal Requirements: Additional Editor Comments (if provided): [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author Reviewer #3: All comments have been addressed Reviewer #4: (No Response) ******** 2. Is the manuscript technically sound, and do the data support the conclusions??> Reviewer #3: Yes Reviewer #4: Partly ****** 3. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #3: Yes Reviewer #4: No ****** 4. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #3: Yes Reviewer #4: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #3: Yes Reviewer #4: Yes ****** Reviewer #3: The research question is interesting, and the methodology employed is generally appropriate. Additionally, the manuscript adheres to the general standards of scientific writing. However, there are some critical points that require attention to align with the publication standards of PLOS ONE. Strengths Relevance of the Study: The research tackles an important question in the field of genes which may influence sweet taste sensivity in people with T2DM, which contributes to advancing knowledge on this subject in african population. Methodological Rigor: The study design is generally sound and detailed, facilitating reproducibility. Clarity and Presentation: The manuscript is structured logically, with clear figures and tables that effectively complement the text. Limitations The authors mention many constraints, even thought you discussion of the limitations—such as potential biases, confounding variables, and the lack of significant results— enhance the transparency and rigor of the study. Suggestions for Improvement Addressing Sample Size Limitations: If feasible, increasing the sample size or discussing why the current size is appropriate given the study design would improve the manuscript. Supplementary Analysis: Including additional analyses (such as dominant or recessive model in statiscal analysis, odds ratio) could help inccrease the robustness of the findings. In general, it's a good article but does not fit Plos One scope as it is now. Reviewer #4: Reviewer #1: Summary Mwakyoma et al. investigated the relationship between genetic variations in TRPV1 (rs4790522, rs8065080) and TAS1R3 (rs307355) genes and sweet taste sensitivity in Zambian adults with and without type 2 diabetes mellitus (T2DM). Using a cross-sectional design (89 participants: 47 T2DM, 42 non-di2DM), they found reduced sweet taste sensitivity in T2DM individuals but no association between the studied SNPs and taste thresholds. The study highlights the need for larger cohorts and emphasizes potential non-genetic factors influencing taste perception in T2DM. Overall Impression The study addresses an under-researched topic in an African population, providing novel baseline data. However, limitations in sample size and methodology reduce the generalizability of conclusions. The relatively small sample size in this study constrained the depth of subsequent analyses. However, given the availability of large-scale GWAS datasets from diverse ethnic populations (e.g., European and East Asian cohorts), the authors could further strengthen the findings through two complementary approaches: 1.Implementing Mendelian randomization (MR) analyses to investigate potential causal relationships between sweet taste sensitivity and T2DM across distinct ethnic groups; 2.Conducting cross-ancestry comparative analyses to evaluate whether the lead SNP effects/alleles associated with these traits are conserved between African populations and other ethnicities. Such trans-ethnic validation would enhance the generalizability of the findings while addressing population-specific genetic architectures. ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #3: No Reviewer #4: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0328172.r003
Revision 2
30 Apr 2025 Author Response Dear editor, Thank you for the communication and consideration of our manuscript. We have spent time to make improvements aligned with both reviewers’ comments and have responded in a point-counter-point manner below. We hope that you find the revised manuscript appropriate for publication. Reviewer #3: The research question is interesting, and the methodology employed is generally appropriate. Additionally, the manuscript adheres to the general standards of scientific writing. However, there are some critical points that require attention to align with the publication standards of PLOS ONE. We thank you for seeing value in our manuscript and hope that the revisions made align with the publication standard of PLOS ONE. Limitations: The authors mention many constraints, even thought you discussion of the limitations—such as potential biases, confounding variables, and the lack of significant results— enhance the transparency and rigor of the study. Suggestions for Improvement: Addressing Sample Size Limitations: If feasible, increasing the sample size or discussing why the current size is appropriate given the study design would improve the manuscript. Unfortunately, we are unable to increase our sample size, this is due to funding restraints. We hope that the publication of our manuscript will warrant further interest in researching our cohort and encourage future studies, including our own, to achieve a larger sample size. We have referenced our sample size limitations throughout the discussion from line. Supplementary Analysis: Including additional analyses (such as dominant or recessive model in statistical analysis, odds ratio) could help increase the robustness of the findings. We have now included additive, dominant and recessive models throughout the manuscript. We also have included a genotype grouping related to those carrying homozygous alternate alleles of the genes studied. We believe this suggested improvement has strengthened our manuscript so we would like to thank you for the consideration. In addition, we have assessed the sample size limitations we have when working with such a novel cohort, and as a result have decided to remove the TRPV1 rs8065080 SNP as the minor allele is not represented enough in our cohort. We believe this makes our reported findings stronger for the remaining two genotypes. The manuscripts results and conclusion have been extensively revise upon your comment, so we hope that you find this version suitable for publication. Reviewer #4: Reviewer #1: Summary: Mwakyoma et al. investigated the relationship between genetic variations in TRPV1 (rs4790522, rs8065080) and TAS1R3 (rs307355) genes and sweet taste sensitivity in Zambian adults with and without type 2 diabetes mellitus (T2DM). Using a cross-sectional design (89 participants: 47 T2DM, 42 non-di2DM), they found reduced sweet taste sensitivity in T2DM individuals but no association between the studied SNPs and taste thresholds. The study highlights the need for larger cohorts and emphasizes potential non-genetic factors influencing taste perception in T2DM. We thank you for seeing value in our manuscript and agree regarding the necessity to encourage further research in African cohorts. Overall Impression The study addresses an under-researched topic in an African population, providing novel baseline data. However, limitations in sample size and methodology reduce the generalizability of conclusions. The relatively small sample size in this study constrained the depth of subsequent analyses. However, given the availability of large-scale GWAS datasets from diverse ethnic populations (e.g., European and East Asian cohorts), the authors could further strengthen the findings through two complementary approaches: 1.Implementing Mendelian randomization (MR) analyses to investigate potential causal relationships between sweet taste sensitivity and T2DM across distinct ethnic groups; 2.Conducting cross-ancestry comparative analyses to evaluate whether the lead SNP effects/alleles associated with these traits are conserved between African populations and other ethnicities. Such trans-ethnic validation would enhance the generalizability of the findings while addressing population-specific genetic architectures. We thank you for providing some methodological alternatives and agree that we are working with a small sample size. However, unfortunately we are unable to increase our sample size nor utilise other databases for this current study. This is due to funding restrains (including personnel). However, we have adapted our approach based on an alternative reviewer’s suggestions, by incorporating an additive, dominant and recessive structure to our results section. We have also excluded one TRPV1 SNP due to poor representation of the alternate genotype. Our work seeks to explore group differences and associations only at this point, with the hope that publication will allow exposure of this under-research cohort leading to future, larger studies. The manuscripts results and conclusion have been extensively revised upon the comments from both reviewers, so we hope that you find this version suitable for publication. Attachments Attachment Submitted filename: Letter to Editor_Author Comments.docx https://doi.org/10.1371/journal.pone.0328172.r004
Decision Letter - Md. Asaduzzaman, Editor Dear Dr. Mwakyoma, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Jul 24 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols . We look forward to receiving your revised manuscript. Kind regards, Md. Asaduzzaman, Ph.D., M. Engg. Academic Editor PLOS ONE Journal Requirements: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author Reviewer #5: All comments have been addressed Reviewer #6: All comments have been addressed ******** 2. Is the manuscript technically sound, and do the data support the conclusions??> Reviewer #5: Yes Reviewer #6: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #5: Yes Reviewer #6: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #5: Yes Reviewer #6: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #5: Yes Reviewer #6: Yes ****** Reviewer #5: 1. Addressing Age Confounding (Most Critical): o In the Results/Discussion: More explicitly discuss the potential impact of the age difference on the observed taste sensitivity differences. Can you quantify how much taste sensitivity typically changes with age based on existing literature to contextualize the findings? o Statistical (if feasible): Even if not for primary analysis, an exploratory age-adjusted analysis (such as ANCOVA for taste threshold with group as factor and age as covariate, or stratifying by age if numbers permit) could provide some insight. If not feasible, state clearly why and reiterate this as a major caveat when interpreting the taste sensitivity difference between groups. 2. Combined Genotype Finding (PwT2DM Preference): o Clearly state the number of individuals in each subgroup for this specific analysis (those with high/low preferred concentration carrying the combined risk/non-risk alleles). o Emphasize its exploratory nature due to the small sample size and potential for it being a chance finding, especially in the context of multiple implicit comparisons. Label it clearly as hypothesis-generating. 3. Discussion of "No Genetic Link": o Continue to emphasize that the "no genetic link" refers specifically to the two SNPs studied in this cohort and under this study's power limitations. It does not rule out the involvement of these genes through other variants, gene-gene/gene-environment interactions, or the involvement of other unstudied taste-related genes. 4. Clarity in Figures/Tables: o Ensure all figures and tables clearly state the 'n' for each group/subgroup being compared, especially for genotype-based analyses. S1 Table 1 (combined genotypes for healthy) and the similar analysis for PwT2DM (Table 3 combined analysis leading to Fig 5) should clearly show participant numbers in each combined genotype category. 5. Future Directions (already good, but could be slightly expanded): o Reiterate the need for larger, ideally age-matched, cohort studies in diverse African populations. o Suggest investigating a wider panel of taste-related genes or using hypothesis-free approaches (e.g., GWAS, if feasible in the future for such cohorts) to identify novel variants associated with taste perception and T2DM risk in African populations. o The paradox of lower sensitivity but lower preference in PwT2DM is intriguing. Future studies could explore this with detailed dietary records, psychological assessments of food reward/craving, and awareness of dietary recommendations. Reviewer #6: To the author, Please correct this information: 1- The paragraph : Collection of saliva samples and single nucleotide polymorphism (SNP) genotyping, Please correct the dominant and recessive alleles for the TRPV1, as both the recessive allele and dominant allele are AC/CC, which is written as the following: TRPV1; Transient Receptor Potential Cation Channel Subfamily V Member 1 gene, rs4790522; CC (wild type), AC, AA, AC/CC (recessive model), AC/CC (dominant model); 2- The reference 33, Pilic L, Mavrommatis Y. Genetic predisposition to salt-sensitive normotension 237 and its effects on salt taste perception and intake. Br J Nutr. 2018;120:721–238 731. doi:10.1017/S0007114518002027 Is investigating the salty taste and the SNPs in the SLC4A5 (rs7571842, rs10177833), SCNN1B (rs239345)and TRPV1 (rs8065080) genes � The primers were not designed but used according to previous studies. � Except the TRPV1 (rs8065080), it does cover the primers and the technique used for the study of TAS1R3 rs307355, and TRPV1 rs4790522 ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #5: No Reviewer #6: Yes: Luma Hassan Alwan Al Obaidy ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org Attachments Attachment Submitted filename: PONE-D-24-49147_R2 reviewer.pdf https://doi.org/10.1371/journal.pone.0328172.r005
Revision 3
13 Jun 2025 Author Response Dear Editor, Thank you again for the communication. We have acknowledged both reviewers’ comments and have responded in a point-counter-point manner below. We hope that you find the revised manuscript appropriate for publication. Reviewer #5: We thank you for your careful overview of our manuscript. We have considered all comments are responded below. 1. Addressing Age Confounding (Most Critical): a. In the Results/Discussion: More explicitly discuss the potential impact of the age difference on the observed taste sensitivity differences. Can you quantify how much taste sensitivity typically changes with age based on existing literature to contextualize the findings? b. Statistical (if feasible): Even if not for primary analysis, an exploratory age-adjusted analysis (such as ANCOVA for taste threshold with group as factor and age as covariate or stratifying by age if numbers permit) could provide some insight. If not feasible, state clearly why and reiterate this as a major caveat when interpreting the taste sensitivity difference between groups. a. Thank you for your comments. We have extended the paragraph in the discussion (paragraph 2; line 355-358) directly related to this result. We hope this provides more clarity. We believe we previously acknowledged the difference in age as a limitation in the discussion paragraph 1 and 6. We have therefore left these sections unchanged. b. ANCOVA or similar analysis with a covariate is not appropriate with the sample size of this study. We previously acknowledged this in the limitations section (line 397-398). Upon your comment, we have extended our original sentence to highlight this further (line 398-399. 2. Combined Genotype Finding (PwT2DM Preference): a. Clearly state the number of individuals in each subgroup for this specific analysis (those with high/low preferred concentration carrying the combined risk/non-risk alleles). b. Emphasize its exploratory nature due to the small sample size and potential for it being a chance finding, especially in the context of multiple implicit comparisons. Label it clearly as hypothesis-generating. a. Thank you for this comment, we believe it increases the quality of our manuscript. We have provided sample size in text (line: 282-283) and in Figures 3 and 5. New figures have been resubmitted with the manuscript. b. The section in the results section that discusses the combined genetic results (line 388-395) highlights the limitations you have discussed in this feedback. We have extended the section with phrases recommended, for further emphasis. 3. Discussion of "No Genetic Link": Continue to emphasize that the "no genetic link" refers specifically to the two SNPs studied in this cohort and under this study's power limitations. It does not rule out the involvement of these genes through other variants, gene-gene/gene-environment interactions, or the involvement of other unstudied taste-related genes. After an in-depth discussion with the authors, we have concluded that line 85-102 and 376-395 emphasise than many studies have shown candidate and polygenic genetic associations with taste. Thus, we have not amended the introduction or discussion. However, we thank you for indicating this phrasing in the abstract and have updated the results and conclusion accordingly (line: 42-53). 4. Clarity in Figures/Tables: Ensure all figures and tables clearly state the 'n' for each group/subgroup being compared, especially for genotype-based analyses. S1 Table 1 (combined genotypes for healthy) and the similar analysis for PwT2DM (Table 3 combined analysis leading to Fig 5) should clearly show participant numbers in each combined genotype category. Supplementary Table 1 already includes the sample size for genotype groupings, if we have misunderstood your comment please advise. As per feedback comment 2 we have updated Figure 3 & 5 accordingly. We have also updated Figures 2,3 and 6 accordingly. 5. Future Directions (already good but could be slightly expanded): a. Reiterate the need for larger, ideally age-matched, cohort studies in diverse African populations. b. Suggest investigating a wider panel of taste-related genes or using hypothesis-free approaches (e.g., GWAS, if feasible in the future for such cohorts) to identify novel variants associated with taste perception and T2DM risk in African populations. c. The paradox of lower sensitivity but lower preference in PwT2DM is intriguing. Future studies could explore this with detailed dietary records, psychological assessments of food reward/craving, and awareness of dietary recommendations. Thank you for the kind words related to our final section. We have discussed you feedback thoroughly and amended the conclusion section, specifically related to point a and b. We hope that you consider this expansion ready for publication. Reviewer #6: We thank you for your careful overview of our manuscript. We have considered all comments are responded below. Please correct this information: 1- The paragraph: Collection of saliva samples and single nucleotide polymorphism (SNP) genotyping. Please correct the dominant and recessive alleles for the TRPV1, as both the recessive allele and dominant allele are AC/CC, which is written as the following: TRPV1; Transient Receptor Potential Cation Channel Subfamily V Member 1 gene, rs4790522; CC (wild type), AC, AA, AC/CC (recessive model), AC/CC (dominant model). Thank you for spotting this typo, it has been corrected (line 192). 2- The reference 33: Pilic L, Mavrommatis Y. Genetic predisposition to salt-sensitive normotension 237 and its effects on salt taste perception and intake. Br J Nutr. 2018; 120:721–238 731. doi:10.1017/S0007114518002027, Is investigating the salty taste and the SNPs in the SLC4A5 (rs7571842, rs10177833), SCNN1B (rs239345) and TRPV1 (rs8065080) genes. • The primers were not designed but used according to previous studies. • Except the TRPV1 (rs8065080), it does cover the primers and the technique used for the study of TAS1R3 rs307355, and TRPV1 rs4790522 Reference 33 is related to the genotyping methodology (extraction, quantification, genotyping), not the assay/primer design. We have revised the section titled “Collection of saliva samples and single nucleotide polymorphism (SNP) genotyping”, which we hope better portrays this (line 158-181). Kind regards, The authors Attachments Attachment Submitted filename: Rebuttal Letter_Round 2_June 2025.docx https://doi.org/10.1371/journal.pone.0328172.r006
Decision Letter - Md. Asaduzzaman, Editor Gene variations and sweet taste sensitivity in Zambian adults with and without type 2 diabetes mellitus. PONE-D-24-49147R3 Dear Dr. Mwakyoma, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Md. Asaduzzaman, Ph.D., M. Engg. Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: Reviewer's Responses to Questions Comments to the Author Reviewer #5: All comments have been addressed Reviewer #6: All comments have been addressed ******** 2. Is the manuscript technically sound, and do the data support the conclusions??> Reviewer #5: Yes Reviewer #6: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? -->?> Reviewer #5: Yes Reviewer #6: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available??> The PLOS Data policy Reviewer #5: Yes Reviewer #6: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English??> Reviewer #5: Yes Reviewer #6: Yes ****** Reviewer #5: Thank you for your edits. A follow up manuscript of more patients will be helpful. Additionally, research on African cohort will be helpful to the community. Reviewer #6: To the Author, The manuscripts entitled (Gene variations and sweet taste sensitivity in Zambian adults with and without type 2 diabetes mellitus) may shed light on the medical issues associated with diabetic patients. Thanks for correcting the manuscript according to the comments. ****** what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy Reviewer #5: No Reviewer #6: Yes: Luma Hassan Alwan Al Obaidy ******** https://doi.org/10.1371/journal.pone.0328172.r007
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Acceptance Letter - Md. Asaduzzaman, Editor PONE-D-24-49147R3 PLOS ONE Dear Dr. Mwakyoma, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset You will receive further instructions from the production team, including instructions on how to review your proof when it is ready. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few days to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Md. Asaduzzaman Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0328172.r008

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