eP170: When cfDNA screening deceives: A rare case of mosaicism for 46,XX/47,XXY with uniparental isodisomy and genital atypia

Sex chromosome aneuploidy (SCA) identified on cell free DNA screening (cfDNA) presents a challenge for both prenatal counseling, and care planning for the infant after delivery. It is well understood that post-natal evaluation must include chromosomal analysis to confirm SCAs and evaluate for mosaicism. This is traditionally achieved using karyotype, with or without FISH for Y-component. The findings are important for diagnosis care planning, including for individuals with Intersex/Differences of Sex Development (I/DSD) traits.