Reviewer’s report
Title: Hyaluronan-binding protein 2 (HABP2) gene variation in women with recurrent miscarriage
Version: 0 Date: 04 May 2017
Reviewer: Gagandeep K Walia
Reviewer's report:
The aim of the present study is to examine the association between three variants in HABP2 gene and  
unexplained  recurrent  miscarriage.  Since  the  prevalence  of  unexplained  recurrent  miscarriage  is  
increasing worldwide, it is important to identify the biological pathways underlying it with the help of  
genetic variants, and HABP2 is one of the important candidate region. The present case-control study  
was conducted in Sweden population and I have some queries and comments on the methodology  
adopted.
Study Participants: The authors have defined 187 cases as women with a history of unexplained  
recurrent miscarriages (3 or more miscarriages in a row). Some of the cases were recruited from  
hospital records (most probably not pregnant at the time of recruitment) while some were recruited  
prospectively which would be pregnant at the time of recruitment. Most of these cases had live births  
after the recurrent miscarriages and thus it is important to understand the treatment that helped them  
carry their pregnancy to interpret the study findings more carefully. Similarly, they recruited 289  
women with atleast one full term pregnancy (without any history of recurrent miscarriage) as controls.  
These  control  women  can  also  have  recurrent  miscarriages  in  future  conceptions  because  of  
unexplained reasons. Therefore, it is advised to recruit non-pregnant women with atleast two successful  
full term pregnancies. The authors are already under-powered to detect small effect sizes of the genetic  
variants and thus it is advised to recruit extremes of comparisons groups (cases and controls) to detect  
the small effect sizes. 
Statistical Analyses: The 3 SNPS were found to be in Hardy-weinberg equillibrium but did not differ  
significantly between the study groups. It is not clear from the manuscript whether the 3 SNPs of  
HABP2  were  in  linkage  disequilibrium.  The  authors  could  have  also  examined  the  haplotype  
frequencies and the association of haplotypes with recurrent miscarriage.      
Results and Discussion: The authors have suggested that the number of previous miscarriages are  
related to live birth rate in future. However, this is largely dependent on the kind of treatment that the  
patient received, which in turn is associated with demographic and socio-economic profile and the  
health seeking behavior of the patients. The authors did not find any significant differences between  
cases and controls with respect to genotype and allelic distribution. It is advised to compare the minor  
allele and genotype frequencies of the control group with the available public databases for Sweden  
population and also worldwide. The authors have not discussed any previous study examining the role  
of the presently studied SNPs in recurrent miscarriages, to be able to compare their findings worldwide,  
except for Altmäe et al. 2011 from their own team. Finally, the role of epigenetics, particularly abrupt  
DNA methylation in the promoter region of HABP2, might be mediating the relationship between  
HABP2 gene and recurrent miscarriage, rather than genetic variation in HABP2.  
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 required 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 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 manuscript:
Needs some language corrections before being published
Declaration of competing interests
Please complete 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  this  
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  
your reply is yes to any, please give details below.
I declare that I have no competing interests
I agree to the open peer review policy of the journal. I understand that my name will be included on my  
report to the authors and, if the manuscript is accepted for publication, my named report including any  
attachments I upload will be posted on the website along with the authors' responses. I agree for my  
report to be made available under an Open Access Creative Commons CC-BY license  
(http://creativecommons.org/licenses/by/4.0/ ). I understand that any comments which I do not wish to  
be included in my named report can be included as confidential comments to the editors, which will not  
be published.
I agree to the open peer review policy of the journal