Mosaic 46,XY,der(15)t(6;15)(q25.1;p12)/46,XY at amniocentesis in a pregnancy associated with a favorable fetal outcome and postnatal decrease of the aneuploid cell line with the unbalanced translocation

• Main Authors: Chih-Ping Chen (Author), Shin-Wen Chen (Author), Yi-Yung Chen (Author), Schu-Rern Chern (Author), Peih-Shan Wu (Author), Fang-Tzu Wu (Author), Yen-Ting Pan (Author), Chen-Chi Lee (Author), Yun-Yi Chen (Author), Wayseen Wang (Author)
• Format: Book
• Published: Elsevier, 2023-01-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

Objective: We present mosaic 46,XY,der(15)t(6;15)(q25.1;p12)/46,XY at amniocentesis in a pregnancy associated with a favorable fetal outcome and postnatal decrease of the aneuploid cell line with the unbalanced translocation. Case report: A 34-year-old primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XY,add(15)(p12)[17]/46,XY[5]. A second amniocentesis at 19 weeks of gestation revealed a karyotype of 46,XY,der(15)t(6;15)(q25.1;p12)[12]/46,XY[8], and array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr arr 6q25.1q27×2-3 with 40% mosaic level. She was referred for genetic counseling. Prenatal ultrasound and the parental karyotypes were normal. A third amniocentesis at 24 weeks of gestation revealed a karyotype of 46,XY,der(15)t(6;15)(q25.1;p12)[23]/46,XY[1], and in uncultured amniocytes, aCGH analysis revealed arr 6q25.1q27×2.5, interphase fluorescence in situ hybridization (FISH) revealed 51% mosaicism (51/100 cells) for partial trisomy 6q and quantitative fluorescence polymerase chain reaction (QF-PCR) analysis determined maternal origin of the aberrant chromosome and excluded uniparental disomy (UPD) 15 and UPD 6. A fourth amniocentesis at 27 weeks of gestation revealed a karyotype of 46,XY,der(15)t(6;15)(q25.1;p12)[21]/46,XY[5], and in uncultured amniocytes, aCGH analysis revealed arr 6q25.1q27×2.46, and interphase FISH revealed 35% mosaicism (35/100 cells) for partial trisomy 6q. At 39 weeks of gestation, a healthy 3028-g male baby was delivered without any phenotypic abnormality. The karyotypes of cord blood, umbilical cord and placenta were 46,XY,der(15)t(6;15)(q25.1;p12)[2]/46,XY,der(15)t(6;15)(q25.1;p12)[29]/46,XY[11] and 46,XY, respectively. When follow-up at age one month, the neonate was phenotypically normal, the peripheral blood had a karyotype of 46,XY (40/40 cells), and FISH analysis on 105 buccal mucosal cells detected five cells with partial trisomy 6q compared with 2% mosaicism (2/100 cells) in the normal control. Conclusion: Mosaicism for an unbalanced translocation with a normal cell line without UPD at amniocentesis can be a transient and benign condition, and can be associated with a favorable fetal outcome and postnatal decrease of the aneuploid cell line.

Item Description

1028-4559
10.1016/j.tjog.2022.01.013