Incidence of sex chromosome aneuploidy in Northern Italy: 27‐year longitudinal study

The availability of cell-free DNA (cfDNA) as a screening tool affords an opportunity for non-invasive identification of sex chromosome aneuploidies (SCAs). This longitudinal study from 1995 through 2021 investigates both the evolution and frequency of prenatal diagnostic testing using amniocentesis (AF) and chorionic villus sampling (CV), and the detection of SCAs through cfDNA samples from a large cohort in Northern Italy.The results of genetic testing from CV and AF samples collected from public and private centers in Italy from 1995 to 2021 were collected. Chromosomal analysis was performed by routine Q-banding karyotype. Regression analyses and descriptive statistics were used to determine population data trends regarding the frequency of prenatal diagnostic testing and the identification of SCAs and correlated with changes in the indications for prenatal diagnostic tests and available screening options.In 27 years, 13,939,526 births and 231,227 invasive procedures were performed. This resulted in the prenatal diagnosis of 934 SCAs. After the commercial introduction of cfDNA use in 2015, the frequency of invasive procedures significantly decreased (P=0.03), while the frequency of prenatal SCA detection significantly increased (P=0.007). The indication for invasive procedures also shifted from advanced maternal age (AMA) to positive cfDNA results for sex chromosome trisomies (SCTs).Our findings suggest the inclusion of SCAs in prenatal cfDNA screening tests can increase the prenatal identification of affected individuals. As the benefits of early ascertainment are increasingly recognized, it is essential that healthcare providers are equipped with comprehensive and evidence-based information regarding the associated phenotypic differences and the availability of targeted effective interventions to improve neurodevelopmental and health outcomes for affected individuals. This article is protected by copyright. All rights reserved.