Clinical course and genetic analysis of a case of the amniocentesis showing chromosome 6 trisomy mosaicism

Objective: Herein, we present a case of mosaic trisomy 6 detected by amniocentesis. Case report: Amniocentesis (G-banding) was performed at 17 weeks of gestation; the results were 47,XY,+6[3]/46,XY[12]. Fetal screening ultrasonography showed no morphological abnormalities, and the parents desired to continue the pregnancy. The infant was delivered vaginally at 39 weeks' gestation. The male infant weighed 3002 g at birth with no morphological abnormalities. G-banding karyotype analysis performed on the infant's peripheral blood revealed 46,XY[20]. FISH analysis revealed trisomy signals on chromosome 6 in 1–4 out of 100 cells from the placenta. The single nucleotide polymorphism microarray of the umbilical cord blood revealed no abnormalities. Methylation analysis of umbilical cord blood revealed no abnormalities in PLAGL1. No disorders were observed at one year of age. Conclusion: When amniocentesis reveals chromosomal mosaicism, it is essential to provide a thorough fetal ultrasound examination and careful genetic counseling to support the couples’ decision-making.