(383) DNA Methylation Analysis of Imprinting Control Regions and Copy Number Variation Sequencing in Early Miscarriage

Objective: To characterize DNA methylation of imprinting control regions (ICR) and copy number variation sequencing (CNV-seq) among early miscarriages in China. CNV-seq detects chromosomal abnormalities in embryos, but the full genetic basis remains unclear. ICR methylation analysis offers insights into gene expression regulation crucial for embryonic development.

Study Design:
We conducted a cross-sectional study of80 patients with early miscarriages (6-8 weeks gestation) in 3 provinces, China from November 2022 to Jun 2024. Chorionic villi of embryonic arrest were collected using hysteroscopy. Specialized in technologies in molecular genetics and reproductive immunology, our centralized lab performed CNV-seq and ICR methylation analysis of 19 loci. These loci include PLAGL1, GRB10, H19/IGF2(IC1), KvDMR1(IC2), SNURF(IC), GNAS-XL, MEST, ZNF331, PEG3, IGF1R, PEG10, DNMT1, DIRAS3, NAP1L5, FAM50B, TRAPPC9 (PEG13), MCTS2P/HM13, and L3MBTL1.

Results: Among these 80 cases (Table 1), chromosomal abnormalities (45%, 36) were detected and ICR methylation abnormalities 28% (22). NESP-AS/GNAS-AS1 was detected in 5 cases (Table 2). PLAGL1 was in 2 cases with transient neonatal diabetes mellitus and KvDMR1(IC2) in 2 with Bechwith-Wiedemann syndrome. Methylation abnormalities were detected in 30% (13/44) of early miscarriages with normal CNV-seq. This ratio varied across maternal age groups [≤ 30 years 18% (2/11), 31-40 years 31% (9/29), and ≥ 41 years 50% (2/4)] and conception methods [PGT-A 20% (2/10), natural 27% (7/26), ICSI 40% (2/5), and IVF 67% (2/3)] (Table 2).

Conclusion:
ICR methylation abnormalities among early miscarriages with normal CNV-seq were prevalent across maternal ages and conception methods, indicating epigenetic causes. Study findings inform future cohort studies in our multi-center consortium with 90,000 annual live births in 16 provinces, China.