Karyotyping and prenatal diagnosis of trisomy 8 mosaicism

Background: Trisomy 8 mosaicism (T8M) is associated with a wide phenotypic spectrum ranging from mild dysmorphism to severe congenital anomalies. We report a case involving a 31-year-old pregnant woman diagnosed with T8M via amniocentesis and molecular karyotyping.Case Presentation: First-trimester screening indicated a high risk for trisomy 21. Bedside ultrasound revealed unexpected multicystic ovaries suggestive of hyperreactio luteinalis. Further investigation through amniocentesis and molecular karyotyping identified a high-level mosaic interstitial duplication of approximately 6.7 Mb in the 8q12.1-q13.1 region.Conclusion: This case highlights the importance of thorough cytogenetic evaluation in pregnancies with abnormal screening results. Accurate diagnosis, including consideration of rare anomalies like T8M, is critical for appropriate counseling and management.