Chromosome abnormalities in 1255 cleavage-stage human embryos

Area of Science:

• Reproductive biology
• Human genetics
• Embryology

Background:

• Chromosome abnormalities are a major cause of implantation failure and miscarriage in IVF.
• Understanding factors influencing embryonic chromosomal health is crucial for improving IVF outcomes.
• Maternal age is a known risk factor for aneuploidy, but its precise impact on other chromosomal abnormalities needs further elucidation.

Purpose of the Study:

• To investigate the relationship between maternal age, embryo morphology, and development rate with chromosome abnormalities in human embryos.
• To analyze the prevalence of polyploidy and aneuploidy in non-viable embryos.
• To establish associations between cleavage stage anomalies and specific chromosomal aberrations.

Main Methods:

• Analysis of 731 non-viable human embryos from IVF treatment.
• Disaggregation of embryos and fluorescence in-situ hybridization (FISH) for chromosome analysis.
• Examination of chromosomes X, Y, 13, 18, 21, and 16.

Main Results:

• Chromosome abnormalities increased with decreasing embryo competence and increasing maternal age.
• Aneuploidy rates rose from 3.1% in embryos from patients aged 20-34 to 17% in those aged 40+.
• Polyploidy and mosaicism were more prevalent in dysmorphic and slowly developing embryos, while aneuploidy was higher in those with good morphology.

Conclusions:

• Clear associations exist between maternal age and aneuploidy, and between cleavage anomalies and mosaicism in non-viable embryos.
• Arrested embryos were predominantly polyploid, suggesting developmental compromise.
• Polyploidy in day 4 embryos indicates potential arrest in extended culture.