Abstract：
OBJECTIVE: To provide genetic counseling and prenatal diagnosis for a fetus with mosaic trisomy 20.
METHODS: Chromosomal karyotyping, chromosomal microarray analysis (CMA) and fluorescence in situ hybridization (FISH) were carried out for a pregnant woman with advanced maternal age.
RESULTS: The karyotype of amniotic fluid sample was 47,XN,+20, whilst the result of CMA was normal. To verify this discrepancy, CMA was performed again with the cultured amniotic fluid, which yielded a result of 47,XN,+20. FISH assay of the amniotic fluid sample was nuc ish(D20Z1)×3[11]/(D20Z1)×2[89], which indicated that about 11% of fetal cells were trisomy 20. After the fetus was born, the karyotype of peripheral blood sample was normal.
CONCLUSIONS: The amniotic fluid sample might be mosaic trisomy 20, and a dominant growth of 47,XN,+20 cells had occurred during the culture process, resulting in alteration of amniotic fluid cell composition. Mosaic trisomy 20 indicated by FISH may be attributed to confined placental mosaicism or somatic mosaicism of trisomy 20.
METHODS: Chromosomal karyotyping, chromosomal microarray analysis (CMA) and fluorescence in situ hybridization (FISH) were carried out for a pregnant woman with advanced maternal age.
RESULTS: The karyotype of amniotic fluid sample was 47,XN,+20, whilst the result of CMA was normal. To verify this discrepancy, CMA was performed again with the cultured amniotic fluid, which yielded a result of 47,XN,+20. FISH assay of the amniotic fluid sample was nuc ish(D20Z1)×3[11]/(D20Z1)×2[89], which indicated that about 11% of fetal cells were trisomy 20. After the fetus was born, the karyotype of peripheral blood sample was normal.
CONCLUSIONS: The amniotic fluid sample might be mosaic trisomy 20, and a dominant growth of 47,XN,+20 cells had occurred during the culture process, resulting in alteration of amniotic fluid cell composition. Mosaic trisomy 20 indicated by FISH may be attributed to confined placental mosaicism or somatic mosaicism of trisomy 20.
摘要：
目的：为20型镶嵌三体胎儿提供遗传咨询和产前诊断。
方法：染色体核型分析，对一名高龄孕妇进行染色体微阵列分析(CMA)和荧光原位杂交(FISH).
结果：羊水样本的核型为47,XN,+20，而CMA结果正常。为了验证这种差异，用培养的羊水再次进行CMA，结果为47，XN，+20.羊水样品的FISH测定为nucish（D20Z1）×3[11]/（D20Z1）×2[89]，这表明大约11%的胎儿细胞是20三体。胎儿出生后，外周血核型正常。
结论：羊水样本可能是马赛克三体20，并且主要生长为47，XN，+20细胞发生在培养过程中，导致羊水细胞成分的改变。FISH指示的马赛克三体20可能归因于三体20的局限性胎盘镶嵌或体细胞镶嵌。
方法：染色体核型分析，对一名高龄孕妇进行染色体微阵列分析(CMA)和荧光原位杂交(FISH).
结果：羊水样本的核型为47,XN,+20，而CMA结果正常。为了验证这种差异，用培养的羊水再次进行CMA，结果为47，XN，+20.羊水样品的FISH测定为nucish（D20Z1）×3[11]/（D20Z1）×2[89]，这表明大约11%的胎儿细胞是20三体。胎儿出生后，外周血核型正常。
结论：羊水样本可能是马赛克三体20，并且主要生长为47，XN，+20细胞发生在培养过程中，导致羊水细胞成分的改变。FISH指示的马赛克三体20可能归因于三体20的局限性胎盘镶嵌或体细胞镶嵌。
