Review for 10.1186/s12876-018-0836-5 (2018)

Reviewer ’s report
Title: Children with cyclic vomiting syndrome: phenotypes, disease burden and mitochondrial
DNA analysis
Version: 0Date: 12 Dec 2017
Reviewer: Robert Issenman
Reviewer's report:This paper has value in providing a description of clinical presentation and symptomatology in a
population of 42 children of Han Chinese origin with Cyclic V omiting Syndrome. The paper iswell written and has some notable findings including the low prevalence of migraine headacheamong family members and a mean duration of hospitalization of 7 +/- 2.4 days, . The weakness ofthe paper relates to the weighting given to mitochondrial analysis which was performed in 13 of 42patients. While early reports suggested a degree of causality, subsequent studies have suggestedthat variation in mitochondrial patterns are more common than previously understood. Review ofthe methods section by a mitochondrial expert suggests that the results have very little meaningunless they are compared to a database comprised of people of the same ethnicity. To quote "theauthors would need to see if the frequency of these variants is different vs a large cohort of peoplewith the same ethnicity." Accordingly, the paper might be re-written as a clinical report describingthe mitochondrial studies but de-emphasizing their significance unless the authors are able to showthat they compared their findings to the appropriate data set.
Are the methods appropriate and well described?
If not, please specify what is required in your comments to the authors.
NoDoes the work include the necessary controls?
If not, please specify which controls are required in your comments to the authors.
NoAre the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
NoAre 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 furtherassessment in your comments to the editors.
I recommend additional statistical review
Quality of written English
Please indicate the quality of language in the manuscript:
AcceptableDeclaration of competing interests
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