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Fertil Steril. 2017 Dec;108(6):1007-1015.e3. doi: 10.1016/j.fertnstert.2017.08.004. Epub 2017 Sep 15.

Abnormally fertilized oocytes can result in healthy live births: improved genetic technologies for preimplantation genetic testing can be used to rescue viable embryos in in vitro fertilization cycles.

Author information

1
Genera, Centers for Reproductive Medicine, Clinica Valle Giulia, Rome, Italy; Genetyx, Molecular Genetics Laboratory, Marostica, Italy. Electronic address: capalbo@generaroma.it.
2
Reproductive Medicine Associates of New Jersey, Basking Ridge, New Jersey.
3
Genera, Centers for Reproductive Medicine, Clinica Valle Giulia, Rome, Italy; Dipartimento di Scienze Anatomiche, Istologiche, Medico Legali e dell'Apparato Locomotore, Università degli Studi di Roma "Sapienza," Rome, Italy.
4
Genera, Centers for Reproductive Medicine, Clinica Valle Giulia, Rome, Italy.
5
Genera, Centers for Reproductive Medicine, Clinica Valle Giulia, Rome, Italy; Genetyx, Molecular Genetics Laboratory, Marostica, Italy.

Abstract

OBJECTIVE:

To test whether abnormally fertilized oocyte (AFO)-derived blastocysts are diploid and can be rescued for clinical use.

DESIGN:

Longitudinal-cohort study from January 2015 to September 2016 involving IVF cycles with preimplantation genetic testing for aneuploidy (PGT-A). Ploidy assessment was incorporated whenever a blastocyst from a monopronuclear (1PN) or tripronuclear zygote (2PN + 1 smaller PN; 2.1 PN) was obtained.

SETTING:

Private IVF clinics and genetics laboratories.

PATIENT(S):

A total of 556 women undergoing 719 PGT-A cycles.

INTERVENTION(S):

Conventional chromosome analysis was performed on trophectoderm biopsies by quantitative polymerase chain reaction. For AFO-derived blastocysts, ploidy assessment was performed on the same biopsy with the use of allele ratios for hetorozygous SNPs analyzed by means of next-generation sequencing (1:1 = diploid; 2:1 = triploid; loss of heterozygosity = haploid). Balanced-diploid 1PN- and 2.1PN-derived blastocysts were transferred in the absence of normally fertilized transferable embryos.

MAIN OUTCOME MEASURE(S):

Ploidy constitution and clinical value of AFO-derived blastocysts in IVF PGT-A cycles.

RESULT(S):

Of the 5,026 metaphase II oocytes injected, 5.2% and 0.7% showed 1PN and 2.1PN, respectively. AFOs showed compromised embryo development (P<.01). Twenty-seven AFO-derived blastocysts were analyzed for ploidy constitution. The 1PN-derived blastocysts were mostly diploid (n = 9/13; 69.2%), a few were haploid (n = 3/13; 23.1%), and one was triploid (n = 1/13; 7.7%). The 2.1PN-derived blastocysts were also mostly diploid (n = 12/14; 85.7%), and the remainder were triploid. Twenty-six PGT-A cycles resulted in one or more AFO-derived blastocysts (n = 26/719; 3.6%). Overall, eight additional balanced-diploid transferable embryos were obtained from AFOs. In three cycles, the only balanced-diploid blastocyst produced was from an AFO (n = 3/719; 0.4%). Three AFO-derived live births were achieved: one from a 1PN zygote and two from 2.1PN zygotes.

CONCLUSION(S):

Enhanced PGT-A technologies incorporating reliable ploidy assessment provide an effective tool to rescue AFO-derived blastocysts for clinical use.

KEYWORDS:

PGT; Ploidy; preimplantation genetic testing

[Indexed for MEDLINE]

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