Novel heterozygous GMNN variants in human early embryonic arrest involving CHK1‑mediated cell cycle dysregulation.

PURPOSE: To investigate the genetic determinants underlying human early embryonic arrest (EA).

METHODS

Whole‑exome sequencing was performed to screen for candidate variants, followed by Sanger sequencing for family‑based validation. The effects of identified variants on Geminin subcellular localization were examined via immunofluorescence, while their impact on CHK1 pathway activation and DNA damage was assessed in HEK‑293 cells using western blot. Patient‑derived arrested embryos were also stained for γH2AX to evaluate DNA damage in situ. In addition, transcriptomic profiling was conducted to explore the broader biological consequences of GMNN variants during early human embryogenesis.

RESULTS

We identified two heterozygous GMNN variants-c.94 T > C (p.Ser32Pro) and c.601_606del (p.Ser201_Ser202del)-in two families presenting with female infertility due to EA. Functional studies revealed that these variants perturb cell cycle regulation, accompanied by CHK1 activation, elevated DNA damage levels, and altered nuclear distribution of Geminin. Transcriptomic analysis of patient embryos further confirmed substantial disruptions in cell cycle-related pathways and increased DNA damage, consistent with the cellular findings.

CONCLUSIONS

Our findings expand the mutational and phenotypic spectrum of GMNN‑associated infertility and reinforce its critical role in cell cycle control during preimplantation development. The distinct transcriptomic signatures arising from different GMNN variants provide mechanistic insights into embryo arrest and offer potential molecular diagnostic markers as well as avenues for individualized therapeutic strategies.