Chromosomal microarray should be performed for cases of fetal short long bones detected prenatally

Purpose To investigate the prevalence of pathogenic and likely-pathogenic variants detected by chromosomal microarray analysis (CMA), among pregnancies with fetal short long bones diagnosed by ultrasound. Methods The study cohort was based on cases of chromosomal microarray analyses performed nationwide for the indication of short long bones. Results CMA was performed in 66 cases of short long bones. There were 4 cases with a pathogenic/likely pathogenic result (6%). The rate of chromosomal abnormalities was significantly higher compared to the background risk for copy number variations (CNVs) in pregnancies with no sonographic anomalies ( P < 0.001). The yield of CMA in our cohort was significantly higher for both isolated and non-isolated cases, for cases in which the lowest estimated bone length percentile was above the 3rd percentile (below 5th percentile), and for cases diagnosed with short long bones after 22 weeks but not for cases diagnosed after 24 weeks. Conclusion The yield of CMA in cases with short long bones (both isolated and non-isolated) is significantly higher than the background risk for chromosomal anomalies in pregnancies with no sonographic anomalies. This suggests that CMA should be offered in pregnancies with a diagnosis of fetal short long bones.