Brief overview of the paper and its main findings

The authors did exome sequencing to an aborted fetus due to skeletal findings during the pregnancy and identified compound heterozygous mutations in PLOD2 which causes Bruck syndrome 2. Major and minor points

The authors identified a novel frameshift mutation in PLOD2. Limitation: The authors did not check the RNA expression of PLOD2 in the fibroblast cells. - The bioinformatics analysis should be described in more detail. The versions of the software, databases and other tools that were used during the anaysis and variant filtering should be provided and cited when needed. The authors did not describe how they annotated the variants and how they found these variants. Did they use an in silico gene panel? - The version number of RefSeq ID of mRNA transcript should be provided. - The manuscript needs proofreading and English language editing. - line 111. conservatism > conservation - line 113. effected > affected - c.191_201+3del would be expected to induce nonsense mediated decay and this should be addressed in the manuscript. The authors should have checked the expression level of PLOD2 in the skin fibroblasts of the fetus. - The title of the manuscript is misleading. "Prenatal Diagnosis" should be removed from the title as the pregnancy was terminated and the diagnosis was done in an aborted fetus. Prenatal diagnosis term should be used for an ongoing pregnancy and should be performed on the CVS or amniocytes. - The references were written as "surname et al year" format in the text but listed with numbers in the references section. Is this the correct way of writing the references?

Conflicts of interest

Do you have any conflicts of interest here? No