Chen Jia, Wu Xingwu, Xu Qiang, Ding Tao, Chen Ge, Chen Houyang, Zou Yongyi, Huang Jialyu, Zhang Ziyu, Tian Lifeng, Zhao Yan, Duan Ranhui, Li Zengming, Wu Qiongfang, Liu Yanqiu
Reproductive Medicine Center, Jiangxi Maternal and Child Health Hospital, 508 West Station Street, Nanchang, Jiangxi, 330006, China.
Jiangxi Key Laboratory of Reproductive Health, Jiangxi Maternal and Child Health Hospital, Nanchang, Jiangxi, 330006, China.
Orphanet J Rare Dis. 2025 Apr 1;20(1):152. doi: 10.1186/s13023-025-03659-7.
Trophectoderm (TE) cell biopsy at the blastocyst stage is currently the most common method used in preimplantation genetic testing for monogenic disorders (PGT-M). However, this approach may result in the wasting of some genetically unaffected embryos because only a proportion of zygotes develop to the blastocyst stage. Unaffected embryos, which degenerated during blastomere-blastocyst transformation, may give birth if transferred before the blastocyst stage and may be of great value to women with a low oocyte count. This study sought to investigate the potential application of polar-body (PB) biopsy in saving more genetically unaffected embryos for women with disease-causing mutations and a limited number of oocytes during PGT-M.
Three couples with female partners who had autosomal dominant or X-linked mutations in IRF6, FMR1, and EDA were recruited. The number of retrieved oocytes was limited to six per cycle. The first and second PBs (PB1 and PB2) of each oocyte were biopsied separately and subjected to multiple displacement amplification (MDA). The genotype of each embryo was determined by analyzing the MDA products of the corresponding PB1 and PB2 using a novel approach that combined direct mutation testing and single nucleotide polymorphism linkage analysis. Mutation-free embryos cryopreserved before the blastocyst stage were chosen for transfer.
In total, four cycles were performed, resulting in the retrieval of 15 oocytes for three couples. The genotype of each embryo was successfully determined. Seven mutation-free embryos were discovered. Three of them were transferred, resulting in two clinical pregnancies, and the birth of two healthy infants. The accuracy of the embryo genotypes was validated by genetic testing of fetuses in the second trimester or at birth.
The PB-based strategy is feasible and effective for determining the mutation-carrier statuses of embryos in PGT-M for maternal mutations. Compared to blastocyst stage detection, this method may save a greater number of genetically unaffected embryos for patients. Further clinical trials are needed to determine whether PB biopsy is more beneficial than TE cell biopsy for women with disease-causing mutations and a limited number of oocytes in PGT-M.
囊胚期滋养外胚层（TE）细胞活检是目前用于单基因疾病植入前基因检测（PGT-M）的最常用方法。然而，这种方法可能会导致一些基因未受影响的胚胎被浪费，因为只有一部分受精卵能发育到囊胚期。在卵裂球 - 囊胚转化过程中退化的未受影响的胚胎，如果在囊胚期之前移植可能会成功妊娠，这对于卵母细胞数量少的女性可能具有重要价值。本研究旨在探讨极体（PB）活检在PGT-M期间为患有致病突变且卵母细胞数量有限的女性挽救更多基因未受影响胚胎方面的潜在应用。
招募了三对夫妇，其女性伴侣在IRF6、FMR1和EDA基因中存在常染色体显性或X连锁突变。每个周期回收的卵母细胞数量限制为6个。分别对每个卵母细胞的第一极体和第二极体（PB1和PB2）进行活检，并进行多重置换扩增（MDA）。通过一种结合直接突变检测和单核苷酸多态性连锁分析的新方法，分析相应PB1和PB2的MDA产物来确定每个胚胎的基因型。选择在囊胚期之前冷冻保存的无突变胚胎进行移植。
总共进行了四个周期，为三对夫妇回收了15个卵母细胞。成功确定了每个胚胎的基因型。发现了7个无突变胚胎。其中3个胚胎进行了移植，导致2例临床妊娠，并诞下2名健康婴儿。通过孕中期或出生时胎儿的基因检测验证了胚胎基因型的准确性。
基于PB的策略对于确定PGT-M中母体突变胚胎的突变携带者状态是可行且有效的。与囊胚期检测相比，该方法可为患者挽救更多基因未受影响的胚胎。需要进一步的临床试验来确定在PGT-M中，对于患有致病突变且卵母细胞数量有限的女性，PB活检是否比TE细胞活检更有益。
