Abstract

STUDY QUESTIONWhat are the genetic causes of oocyte maturation defects?SUMMARY ANSWERA homozygous splicing variant (c.788 + 3A>G) in TATA-box binding protein like 2 (TBPL2) was identified as a contributory genetic factor in oocyte maturation defects.WHAT IS KNOWN ALREADYTBPL2, a vertebrate oocyte-specific general transcription factor, is essential for oocyte development. TBPL2 variants have not been studied in human oocyte maturation defects.STUDY DESIGN, SIZE, DURATIONTwo infertile families characterized by oocyte maturation defects were recruited for whole-exome sequencing (WES).PARTICIPANTS/MATERIALS, SETTING, METHODSGenomic DNA was extracted from peripheral blood for WES analysis. Sanger sequencing was performed for data validation. Pathogenicity of variants was predicted by in silico analysis. Minigene assay and single-oocyte RNA sequencing were performed to investigate the effects of the variant on mRNA integrity and oocyte transcriptome, respectively.MAIN RESULTS AND THE ROLE OF CHANCEA homozygous splicing variant (c.788 + 3A>G) in TBPL2 was identified in two unrelated families characterized by oocyte maturation defects. Haplotype analysis indicated that the disease allele of Families 1 and 2 was independent. The variant disrupted the integrity of TBPL2 mRNA. Transcriptome sequencing of affected oocytes showed that vital genes for oocyte maturation and fertilization were widely and markedly downregulated, suggesting that a mutation in the transcriptional factor, TBPL2, led to global gene alterations in oocytes.LIMITATIONS, REASONS FOR CAUTIONLimitations include the lack of direct functional evidence. Owing to the scarcity of human oocyte samples, only two immature MI oocytes were obtained from the patients, and we could only investigate the effect of the mutation at the transcriptional level by high-throughput sequencing technology. No extra oocytes were obtain