Can Dai1, Liang Hu1,2,3,4, Fei Gong1,2,3, Yueqiu Tan1,2,3, Sufen Cai1,2, Shuoping Zhang1,2, Jing Dai1,2, Changfu Lu1,2,3, Jing Chen2, Yongzhe Chen2, Guangxiu Lu1,3,4, Juan Du5,6,7, Ge Lin8,9,10,11. 1. Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China. 2. Institute of Reproductive and Stem Cell Engineering, School of Basic Medicine, Central South University, Changsha, China. 3. Key Laboratory of Stem Cells and Reproductive Engineering, Ministry of Health, Changsha, China. 4. National Engineering and Research Center of Human Stem Cell, Changsha, China. 5. Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China. tandujuan@csu.edu.cn. 6. Institute of Reproductive and Stem Cell Engineering, School of Basic Medicine, Central South University, Changsha, China. tandujuan@csu.edu.cn. 7. Key Laboratory of Stem Cells and Reproductive Engineering, Ministry of Health, Changsha, China. tandujuan@csu.edu.cn. 8. Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China. linggf@hotmail.com. 9. Institute of Reproductive and Stem Cell Engineering, School of Basic Medicine, Central South University, Changsha, China. linggf@hotmail.com. 10. Key Laboratory of Stem Cells and Reproductive Engineering, Ministry of Health, Changsha, China. linggf@hotmail.com. 11. National Engineering and Research Center of Human Stem Cell, Changsha, China. linggf@hotmail.com.
Abstract
PURPOSE: The oocyte-borne genetic causes leading to fertilization failure are largely unknown. We aimed to identify novel human pathogenic variants (PV) and genes causing fertilization failure. METHODS: We performed exome sequencing for a consanguineous family with a recessive inheritance pattern of female infertility characterized by oocytes with a thin zona pellucida (ZP) and fertilization failure in routine in vitro fertilization. Subsequent PV screening of ZP2 was performed in additional eight unrelated infertile women whose oocytes exhibited abnormal ZP and similar fertilization failure. Expression of ZP proteins was assessed in mutant oocytes by immunostaining, and functional studies of the wild-type and mutant proteins were carried out in CHO-K1 cells. RESULTS: Two homozygous s PV (c.1695-2A>G, and c.1691_1694dup (p.C566Wfs*5), respectively) of ZP2 were identified in the affected women from two unrelated consanguineous families. All oocytes carrying PV were surrounded by a thin ZP that was defective for sperm-binding. Immunostaining indicated a lack of ZP2 protein in the thin ZP. Studies in CHO cells showed that both PV resulted in a truncated ZP2 protein, which might be intracellularly sequestered and prematurely interacted with other ZP proteins. CONCLUSION: We identified loss-of-function PV of ZP2 causing a structurally abnormal and dysfunctional ZP, resulting in fertilization failure and female infertility.
PURPOSE: The oocyte-borne genetic causes leading to fertilization failure are largely unknown. We aimed to identify novel human pathogenic variants (PV) and genes causing fertilization failure. METHODS: We performed exome sequencing for a consanguineous family with a recessive inheritance pattern of female infertility characterized by oocytes with a thin zona pellucida (ZP) and fertilization failure in routine in vitro fertilization. Subsequent PV screening of ZP2 was performed in additional eight unrelated infertile women whose oocytes exhibited abnormal ZP and similar fertilization failure. Expression of ZP proteins was assessed in mutant oocytes by immunostaining, and functional studies of the wild-type and mutant proteins were carried out in CHO-K1 cells. RESULTS: Two homozygous s PV (c.1695-2A>G, and c.1691_1694dup (p.C566Wfs*5), respectively) of ZP2 were identified in the affected women from two unrelated consanguineous families. All oocytes carrying PV were surrounded by a thin ZP that was defective for sperm-binding. Immunostaining indicated a lack of ZP2 protein in the thin ZP. Studies in CHO cells showed that both PV resulted in a truncated ZP2 protein, which might be intracellularly sequestered and prematurely interacted with other ZP proteins. CONCLUSION: We identified loss-of-function PV of ZP2 causing a structurally abnormal and dysfunctional ZP, resulting in fertilization failure and female infertility.
Entities:
Keywords:
Causative gene; Exome sequencing; Fertilization failure; ZP2; Zona pellucida
Authors: Yongzhe Chen; Zesong Wang; Yueren Wu; Wenbin He; Juan Du; Sufen Cai; Fei Gong; Guangxiu Lu; Ge Lin; Can Dai Journal: Front Genet Date: 2021-05-19 Impact factor: 4.599