A Case of Sex Discordant Dichorionic Diamniotic Twins after Single Embryo Transfer and the Importance of Zygosity Testing

Round 1

Reviewer 1 Report

This report presents a case of SET resulting in twins with sex discordance, indicating possible dizygosity. This topic is interesting.

1.      There was no zygosity testing conducted, thus it is unknown if the twins are monozygotic or dizygotic. PGT-A was not performed in this study. Therefore, it is difficult to draw conclusions with limited data. Natural conception after embryo transfer needs to be avoided after communicating with the patient, but monozygotic twins cannot be avoided.

2.      Postnatal genetic testing confirmed 46,XX and 46,XY offspring. Multiple gestations may still occur in the setting of SET and zygosity testing in these instances would better elucidate our understanding of this occurrence.

line 83: The patient and her husband were counseled on zygosity testing to determine if the twins resulted from one embryo or two, but they declined this testing.

If doing karyotype means they are not mosaic? On the other hand, if the baby's karyotype is normal and there is no abnormality, whether it is necessary to perform zygosity testing is worthy of careful consideration. The authors should explain what are the necessary conditions for evaluating zygosity testing for the generation of monozygotic 46,XX and 46,XY mosaic twins hypothetically caused by 47,XXY zygote? Why is it necessary? In addition, is it necessary to consider 47,XXY and 46,XO mosaic twins for zygosity testing?

3.      Pathology reports of the placental and membrane findings reported diamniotic, dichorionic twins. Furthermore, the generation of monozygotic 46,XX and 46,XY mosaic twins hypothetically caused by 47,XXY zygote.

How likely is it to happen? Please indicate if there is any published literature.

4.      line 55: Her oral dose of estradiol weas 6mg: error typing

5. line 44: A 34-year-old G1P0010 female with: the sentence is not clear.

6. Title: The Role of Zygosity Testing?? Because this study does not perform zygosity testing on the results of twins, perhaps authors should explain this more.

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Author Response

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Reviewer 2 Report

Vatti et al. describes an interesting case report of a twin pregnancy after SET. 

They advocate the role for zyogisty testing. 

I only have 1 minor remark: typing error:

linde 55: her oral dose of estradiol weas (-> was) 6mg.

It could be nice to have the picture of the 3BB embryo also in the paper. 

These case reports are very important and balance the literature on monozygotic twins after blastocyst SET. 

Author Response

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