Report on noninvasive prenatal testing: classical and alternative approaches.

Area of Science:

• Genetics
• Prenatal Diagnostics
• Bioinformatics

Background:

• Traditional prenatal aneuploidy testing methods have limitations including accuracy and safety concerns.
• Noninvasive prenatal testing (NIPT) based on genetics has emerged as a superior alternative.
• NIPT has been rapidly adopted globally following successful clinical trials.

Purpose of the Study:

• To evaluate the efficacy of NIPT methods in a Moscow, Russia cohort.
• To assess alternative approaches for NIPT, focusing on fetal DNA fraction determination.
• To validate novel methods for improved NIPT reliability.

Main Methods:

• Massive parallel sequencing was used to analyze 1012 samples for chromosome coverage.
• Two NIPT approaches were investigated: maternal/fetal differential methylation and allelic difference.
• Chromosome Y representation was measured using real-time PCR and whole-genome sequencing.

Main Results:

• The maternal/fetal differential methylation approach yielded unstable results.
• The allelic difference method proved promising for NIPT.
• Chromosome Y representation measures by PCR and sequencing were highly correlated (r=0.94).
• A novel maternal/fetal allelic difference method showed good correlation with chromosome Y estimates (r=0.74).

Conclusions:

• The allelic difference method is a promising approach for NIPT, applicable to both sexes.
• Accurate determination of fetal cell-free DNA fraction is crucial for reliable NIPT results.
• Further large-scale trials are recommended for the novel allelic difference-based NIPT method.