MCM8 variants in two patients with primary ovarian insufficiency: clinical findings and

Backgrounds: Pediatric-onset primary ovarian insufficiency (POI) presents distinct clinical challenges, including delayed puberty or growth retardation. Previously, we reported a Chinese family with POI harboring compound heterozygous variants (p.C242R and p.S445*) in Objective: This study describes clinical findings of pediatric-onset POI patients with compound heterozygous Methods: HeLa cell models were used to overexpress double-mutant (p.C242R and p.S445*) or wild-type MCM8. Functional consequences were evaluated using immunofluorescence staining, flow cytometry, and western blotting to assess DNA damage repair, cell cycle and apoptosis. Co-immunoprecipitation coupled with mass spectrometry (CoIP-MS/MS) was used to screen the disrupted protein interactome. Cut&Tag and mRNA-seq analyses were used to examine chromatin-binding-associated changes and transcriptomic alterations. Results: Ovarian tissues from POI patients exhibited reduced MCM8 expression and increased apoptosis. Cells expressing the artificial double-mutant MCM8 construct showed delayed resolution of DNA damage, as indicated by persistent γ-H2AX accumulation, and altered recruitment of DMC1 and RAD51. These changes were accompanied by S-phase accumulation and increased apoptosis. CoIP-MS/MS analysis identified altered interaction between double-mutant MCM8 and MCM6, suggesting possible changes in replication-associated protein interactions. Integrated CUT&Tag and RNA-seq analyses identified MCM8-associated chromatin-binding changes and transcriptomic alterations involving candidate genes enriched in ovarian survival and metabolic pathways, including the PI3K/AKT signaling pathway. Conclusions: These specific