Abstract for presentation at 11th International Congress of Human Genetics

Comparison of FISH and conventional cytogenetic analysis in 87 amniotic fluid samples for prenatal diagnosis

  • Sun Kyung Oh, IRMP, MRC, Dept. OB&GY, College of medicine, Seoul National University, Korea
  • Mi Jung Woo, IRMP, MRC, College of medicine, Seoul National University, Korea
  • Nam Hee Song, IRMP, MRC, College of medicine, Seoul National University, Korea
  • Sook Ryoung Kim, IRMP, MRC, College of medicine, Seoul National University, Korea
  • Kyung Hun Kwon, IRMP, MRC, College of medicine, Seoul National University, GenDix Inc., Korea
  • Hyo Jin Lee, IRMP, MRC, College of medicine, Seoul National University, Korea
  • Young Min Choi, IRMP, MRC, Dept. OB&GY, College of medicine, Seoul National University, Korea
  • Shin Yong Moon, IRMP, MRC, Dept. OB&GY, College of medicine, Seoul National University, Korea

    • Fluorescence in situ hybridization (FISH) of uncultured amniocytes using chromosome-specific DNA probes is a useful method for rapid screening for the most common types of aneupoidy. This study has described 87 amniotic fluid interphase using molecular cytogenetic techniques in prenatal diagnosis from January to December 2005. FISH of uncultured amniotic fluid cells were performed on 87 samples using specific probes for chromosomes 18, 21, and X. And karyotypes from conventional cytogenetic analysis were compared to the FISH results. Amniotic fluid samples were obtained between the 15th and 23th weeks of gestation. Three cases of trisomy 21 among 87 samples were numerical chromosomal anomalies detectable by interphase FISH. There were nuc ish 21q22x3[133], nuc ish 21q22x3[47]/21q22x2[53], and nuc ish 21q22x3[29]/21q22x2[119]. Compared to cytogenetic results, the one mosaic trisomy 21 of FISH results was 47, XY,+21, and other mosaic trisomy 21 was 47,XY,+21[2]/46,XY,[63]. The major indication was maternal serum maker screening positive (77.0%). The indication for three anomalies was all maternal serum maker screening positive. Conventional cytogenetic analysis revealed chromosomal anomalies such as 46,XX,t(5;16), 46,XX,inv(9), and 46,XY,small Y not detectable by FISH. In the present study, it found that direct FISH is a reliable technique for the rapid prenatal diagnosis of trisomy 21. However, the chromosomal anomalies undetected by FISH analysis confirmed the need for conventitonal cytogenetic analysis. Genetic counseling is an important to explain the limitations of interphase FISH on uncultured amniocytes.

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