LETTER TO THE EDITOR Re: First live birth after fertility preservation using vitrification of oocytes in a woman with mosaic Turner syndrome

Purpose To report the case of a young woman diagnosed with Turner syndrome (TS) who achieved a live birth using her own oocytes that had been vitrified for fertility preservation. Methods A 25-year-old woman with mosaic (45,X/46,XX) TS was referred for fertility preservation (FP) counseling. Serum anti-Müllerian hormone (AMH) level was normal (6.4 µg/L). In view of the unpredictable rate of follicle loss in TS individuals, she requested FP and underwent two cycles of ovarian stimulation (OS) for oocyte cryopreservation (OoC) using a GnRH antagonist protocol and recombinant follicle stimulating hormone (rFSH), 200–250 IU daily for 8 resp. 12 days. Results In total, 29 metaphase II oocytes (MII) were vitrified after OS. After conceiving spontaneously and achieving a live birth, she returned to the clinic five years after OoC with a desire for pregnancy using in vitro fertilization (IVF) of her cryopreserved oocytes and preimplantation genetic testing (PGT-A). All 29 MII oocytes were thawed; 23 oocytes survived (79.3%) and were inseminated with partner sperm using intracytoplasmic sperm injection (ICSI). Thirteen oocytes were fertilized resulting in three good quality blastocysts which were vitrified after trophectoderm biopsy for PGT-A using array-CGH. Two blastocysts were found to be euploid. One was thawed and transferred to the uterus using a HRT priming protocol. An uneventful pregnancy occurred. The patient delivered a healthy baby girl weighing 3490 g at 40 weeks of gestation. Conclusions We report the first live birth achieved using cryopreserved oocytes in a woman diagnosed with mosaic TS. Cryopreservation of oocytes after ovarian stimulation is a realistic option for FP in selected post menarche individuals with mosaic TS. Whether PGT-A may reduce the risk of pregnancy loss in TS has to be confirmed by further studies.