Objective: To evaluate the prevalence of mosaicism in chorionic villus sampling (CVS) samples after chromosomal microarray (CMA) and clinical outcome of pregnancies affected by confined placental mosaicism. Method: We retrieved all results from CMA, array-based comparative genomic hybridization, on CVS samples from January 2011 to November 2017 from Central and North Denmark Regions. Mosaic results from uncultured chorionic villi, cytotrophoblasts and mesenchymal cells, after CVS and follow-up on amniocytes, fetal tissue, or postnatal blood were studied and matched with clinical data from The Danish Fetal Medicine Database. Results: Prevalence of mosaicism was 93 out of 2,288 (4.1%) CVS samples of which 17 (18.3%) concerned submicroscopic copy number variations (CNVs) <10 Mb.Follow-up analyses were performed in 62 cases. True fetal mosaicism (TFM) was confirmed in 18.4% (7/38) when mosaicism involved whole chromosome aneuploidy and in 25.0% (6/24), when involving a CNV (P = .59). Median birth weight z-score was higher in cases of confined placental mosaicism for a CNV (0.21) than cases involving whole chromosomes (−0.74) (P = .02).Conclusion: Prevalence of mosaicism in CVS samples is higher after CMA on uncultured tissue than after conventional karyotyping on cultured tissue. The risk of TFM is equally high in cases of mosaicism for CNVs and whole chromosomes.

Background Congenital heart disease (CHD) is a well-known co-occurring condition in Down syndrome (DS). We aimed to review the literature to evaluate the current evidence to address key questions. Methods A series of key questions were formulated a priori to inform the search strategy and review process. These addressed the topics of prevalence, type of CHD, severity, and screening. Using the National Library of Medicine database, PubMed, detailed literature searches were performed. The quality of available evidence was then evaluated, the existing literature was summarized, and knowledge gaps were identified. Results Fifty-six relevant original articles were identified which addressed at least one key question. Study details, including: research design, internal validity, external validity, and relevant results are presented. The total prevalence of CHD reported in DS ranged from 20 to 57.9%. In later decades, the prevalence remained constant at 40—55%. The types and classification of CHD varied considerably between studies. Some studies indicate a trend towards a milder phenotype, but this was not consistent. Over time, some studies observed an improved prognosis for CHD in DS. Studies investigating screening for CHD by physical examination, chest X-ray, and electrocardiogram report sensitivities of 71–95%. Conclusion To further improve knowledge on CHD in DS, we suggest that future studies cover a wide range of nations and regions, with a longitudinal design, and account for potential confounding factors.

Down syndrome is a commonly encountered condition within genetic counseling. In contrast to other, rarer genetic causes of intellectual disability, public narratives about Down syndrome exist (Thomas, 2021). In addition, the syndrome stands out as one of few genetic conditions for which prenatal screening has been widely adopted in recent decades (Boyd et al., 2008).Guidelines for communicating a diagnosis of Down syndrome recommend the genetic counseling to include the potential future family life (Sheets, Crissman, et al., 2011). Studies suggest that both parents and genetic counselors believe that information about the