Comprehensive Cytogenetic Analysis Reveals Mosaicism in Newborn with Negative Prenatal Down Syndrome Screening: A Case Report.

BACKGROUND Down syndrome, or trisomy 21, is one of the most common chromosomal disorders associated with intellectual disability. Prenatal screening is a proactive approach to identify fetuses with common chromosomal abnormalities. Mosaicism is one of the causes of false-negative results in prenatal screening for Down syndrome.