Detection of no isochromosome 20q by interphase fluorescent in situ hybridization on uncultured amniocytes in a pregnancy with mosaic isochromosome 20q in cultured amniocytes at amniocentesis

作者：Chen Chih Ping^*; Su Jun Wei; Chern Schu Rern; Kuo Yu Ling; Wu Peih Shan; Lee Meng Shan; Yang Chien Wen; Wang Wayseen

来源：Taiwanese Journal of Obstetrics & Gynecology, 2015, 54(1): 58-61.

DOI：10.1016/j.tjog.2014.12.002

• amniocentesis
• amniocytes
• isochromosome 20q
• mosaicism
• prenatal diagnosis

Objective: To present prenatal diagnosis and molecular cytogenetic characterization of mosaic isochromosome 20q at amniocentesis.
Materials and methods: A 36-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age, and conventional cytogenetic analysis revealed a karyotype of 46,XY,i(20)(q10)[12]/46.XY[7]. Repeated amniocentesis was performed at 20 weeks of gestation. During repeated amniocentesis, array comparative genomic hybridization (aCGH), interphase fluorescence in situ hybridization (FISH), and quantitative fluorescent polymerase chain reaction (QF-PCR) were performed on uncultured amniocytes. and conventional cytogenetic analysis and interphase FISH were performed on cultured amniocytes.
Results: Conventional cytogenetic analysis of cultured amniocytes revealed a karyotype of 46,XY,i(20)(q10)[4]/46,XY[16]. Interphase FISH analysis on 217 uncultured amniocytes did not detect isochromosome 20q, aCGH on the DNA extracted from uncultured amniocytes showed no genomic imbalance, and QF-PCR analysis on the DNA extracted from uncultured amniocytes excluded uniparental disomy 20 (UPD 20). Interphase FISH analysis on 115 cultured untouched amniocytes revealed 13% (15/115 cells) mosaicism for isochromosome 20q.
Conclusion: Mosaic isochromosome 20q detected at amniocentesis can be a cell culture artifact. Detailed ultrasound examination, performing interphase FISH and/or aCGH on uncultured amniocytes for confirmation of true mosaicism, and performing QF-PCR to exclude UPD 20 may be useful under such a circumstance.

• 出版日期2015-2
• 单位中国医科大学