Review for 10.1186/s12876-017-0636-3 (2017)

Reviewer ’s report  
 
Title: Novel NBAS mutations and fever -related recurrent  acute liver failure in Chinese 
children：a retrospective study  
 
Version: 0 Date: 25 Nov 2016  
 
Reviewer: Christian Staufner  
 
Reviewer's report:  
 
Li et al present a WES study of five individuals with RALF. It is the first study on the etiology of 
RALF in China. In thre e of five individuals with RALF, biallelic mutations in NBAS were 
identified. NBAS is known as a relatively frequent cause of RALF in the European population. 
All NBAS mutations identified in this work have not been reported previously. The clinical 
phenot ype of the three NBAS patients resembles the known phenotype of patients with NBAS -
related RALF. The study does not elucidate new aspects of pathomechanism.  
 
 
 
 
General: write gene names in italic (NBAS)  
 
 
Introduction  
 
The authors state that "the etiology o f large proportion of instances of pediatric RALF remains 
unexplained", without presenting a reference. I doubt this. Please provide evidence or rewrite.  
 
 
"The causes of RALF in non -Europe are unexplored" is only partly true, as the cited studies (6 -
10) include individuals from USA and Cuba and another study on individuals with RALF (Capo -
Chichi et al 2015) includes individuals from Libanon.  
 
 
Very short intro duction. Consider to include information o n the role of NBAS in RALF, which 
has been shown to be a typical and relatively frequent cause of RALF in European patients (6 
patients from 5 families with NBAS -mutations out of 15 patients, Haack et al 2015).  
 
 
 
 
Methods  
 
Page 4, Line 43 "patient 4, who is (not are) from consanguineous parents and has (not have) two 
healthy sisters".  
Include details about all other siblings and family history (deceased siblings only mentioned in 
text of figure 1 so far)  
 
Include detail s about age at onset of ALF episodes for all 5 patients in the text.  
 
 
Page 4, Line 51: define fever/feverish (> 38.5°C?). Consider to write febrile infection instead of 
fever if correct.  
 
 
 
Page 5, "Liver biopsy"  
 
Several sentences are cryptic (instead of "pa tient 2 received 2 months after the second liver 
crisis" say "in patient 2,liver biopsy was performed 2 months after the second liver crisis"). 
Rewrite this paragraph. Include age at liver biopsies in the text.  
 
 
Exome sequencing analysis -This paragraph is partly cryptic. Rewrite. It remains unclear why 
two different protocols were used. There is a great overlap between the two strategies. Have both 
protocols been used in all 5 patients?  
 
 
Instead of having 5 additional files, consider including the supplemen tary information in one file.  
 
 
"scoring < 10 in the Genesky in -house database" please explain.  
 
 
Page 6, line 40: write "in the first protocol", and page 7 line 1 "in the second protocol" to 
facilitate reading.  
 
 
Page 6, line 57. I don't understand (4). Is it not included in (1)?  
 
 
 
 
 
RESULTS  
 
Page 8: Include the combination of identified NBAS variants in the respective patients in the text 
(patient 1: ms + fs), patient 2 (ms + ms), patient 3 (ms + splice), not only list them by mutation 
type.  
 
Page 8, line 29: p.E1 90X or p.E196X ? (see figure 1!)  
Page 9: include concentration ranges of bile acids and activities of ALT and AST. Add 
information on INR/hepatic coagulopathy. Add information on severity of liver crises in relation 
to age at crisis. Add information on the  causes of fever (I assume infections, bacterial or viral?). 
Add information on therapeutic management during liver crises.  
 
Include more details on extrahepatic symptoms or comorbidities, even if absent. Have the 
patients been prospectively elevated for mi nor facial dysmorphism including hypotelorism, 
immune deficiency including NK cell function and hypogammaglobulinemia, Pelger huet 
anomaly, optic atrophy? Skeletal dysplasia, fractures? Congnitive and motor development?  
 
 
 
 
DISCUSSION  
 
Page 10: relation of f requency and severity of ALF with age is discussed, but had no details are 
provided in results.  
 
 
Patient 2 has two ms mutations in NBAS previously not related to RALF. However, no 
experiments validating the pathogenicity are performed (IHC NBAS, western blot NBAS). This 
should be discussed (or, preferably, western blot or IHC should be performed at le ast in patient 
2). 
 
 
 
Table 1  
 
Provide age at last assessment.  
 
Provide age at last ALF (and consider including age at last liver crisis without ALF).  
 
Episodes of RALF vs Epdisodes of ALF: You have defined RALF as >1 liver crisis with at least 
one ALF, but it does not make sense to me to count "episodes of RALF" as sum of episodes of 
ALF + episodes of liver crisis without ALF. I suggest to delete the row "Episodes of RALF" in 
table 1.  
 
 
Was Hepato -  and splenomegaly present in the interval or during crises?  
 
 
Instead of "stature, centile" I suggest "Body height (SDS)"  
 
 
Details on when liver biopsy was done and clinical status at biopsy are provided, but no results 
of biopsy. Include results (in keywords).  
Presence of fever before ALF is an important feature of  this study, but not included in table 1. 
Consider inclusion.  
 
 
Include genetic findings in table 1.  
 
 
 
Suppl. Files 2 -6: double check grammar.  
 
 
 
 
 
Are the methods appropriate and 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 r equired in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately 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  
addi tional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
Not relevant to this manuscript  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Not suitable for publication unless extensively edited  
 
 
 
 
 
 
Declaration of competing interests  
Please comp lete 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 t his 
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 now 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 to 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 interests' 
below.  If you r reply is yes to any, please give details below.  
 
I declare that I have no competing interests.  
 
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