Trisomy 20
Trisomy 20 is a genetic abnormality in which individuals have an extra copy of chromosome 20. Complete trisomy 20 is rare and believed to be incompatible with life. A mosaic form of trisomy 20, in which only some cells or tissues contain the extra chromosome, is a relatively commonly encountered chromosomal abnormality found during prenatal testing, and c. 90% result in a normal phenotype. However, despite the absence of a consistent phenotype, certain findings have been reported across multiple cases of mosaic trisomy 20. These include an array of morphological findings, developmental delays, and learning disabilities. Beyond physical manifestations, a wide range of developmental and learning delays have also been reported.
Montplaisir R, Lee E, Moreno-De-Luca D, Myers WC. Mosaic trisomy 20 and mitigation in capital crimes sentencing: A review and case report. Behav Sci Law. 2019 Sep;37(5):512-521. doi: 10.1002/bsl.2422. Epub 2019 Aug 7. PMID: 31389076.
Montplaisir R, Lee E, Moreno-De-Luca D, Myers WC. Mosaic trisomy 20 and mitigation in capital crimes sentencing: A review and case report. Behav Sci Law. 2019 Sep;37(5):512-521. doi: 10.1002/bsl.2422. Epub 2019 Aug 7. PMID: 31389076.
Fetuses with low-level mosaic trisomy 20 at amniocentesis can have a favorable outcome. Molecular cytogenetic analysis on uncultured amniocytes is useful for confirmatory diagnosis of the mosaic level in case of mosaic trisomy 20 at amniocentesis with different mosaic levels at different amniocenteses.
Chen CP, Kuo YL, Chern SR, Wu PS, Chen SW, Wu FT, Chen LF, Wang W. Prenatal diagnosis of low-level mosaic trisomy 20 by amniocentesis in a pregnancy with a favorable outcome. Taiwan J Obstet Gynecol. 2020 Mar;59(2):327-330. doi: 10.1016/j.tjog.2020.01.026. PMID: 32127159.
Chen CP, Kuo YL, Chern SR, Wu PS, Chen SW, Wu FT, Chen LF, Wang W. Prenatal diagnosis of low-level mosaic trisomy 20 by amniocentesis in a pregnancy with a favorable outcome. Taiwan J Obstet Gynecol. 2020 Mar;59(2):327-330. doi: 10.1016/j.tjog.2020.01.026. PMID: 32127159.
NIPT Testing:
In Group I, seventeen (17/37, 45.95%) women with suspected fetal aneuploidy received amniocentesis, which confirmed 100% (10/10) of positive trisomy 21 samples, 100% (1/1) of trisomy 18, 100% (1/1) of sex chromosome abnormality, 0% (0/2) of trisomy 16, 0% (0/2) of trisomy 13, and 0% (0/1) of trisomy 20 and 13.
Du Y, Lin J, Lan L, Dong Y, Zhu J, Jiang W, Pan X, Lu Y, Li D, Wang L. Detection of chromosome abnormalities using current noninvasive prenatal testing: A multi-center comparative study. Biosci Trends. 2018 Jul 17;12(3):317-324. doi: 10.5582/bst.2018.01044. Epub 2018 Jun 28. PMID: 29952350.
In Group I, seventeen (17/37, 45.95%) women with suspected fetal aneuploidy received amniocentesis, which confirmed 100% (10/10) of positive trisomy 21 samples, 100% (1/1) of trisomy 18, 100% (1/1) of sex chromosome abnormality, 0% (0/2) of trisomy 16, 0% (0/2) of trisomy 13, and 0% (0/1) of trisomy 20 and 13.
Du Y, Lin J, Lan L, Dong Y, Zhu J, Jiang W, Pan X, Lu Y, Li D, Wang L. Detection of chromosome abnormalities using current noninvasive prenatal testing: A multi-center comparative study. Biosci Trends. 2018 Jul 17;12(3):317-324. doi: 10.5582/bst.2018.01044. Epub 2018 Jun 28. PMID: 29952350.
Amniotic fluid cell karyotyping revealed a trisomy 20 (47,XY,+20) with 100% trisomic cells (38/38); however, a subsequent cordocentesis revealed a normal male karyotype. Moreover, a follow-up ultrasonographic examination did not reveal any major congenital malformations, and a healthy male infant was delivered subsequently at an appropriate gestational age without obvious anomalies.
Maeda K, Imoto I, Kaji T, Yoshida Y, Nakayama S, Irahara M. Case of non-mosaic trisomy 20 in amniotic fluid cultures without anomalies in the fetus: cytogenetic discrepancy between amniocytes and fetal blood. J Obstet Gynaecol Res. 2015 Jan;41(1):141-4. doi: 10.1111/jog.12488. Epub 2014 Aug 28. PMID: 25164874.
Maeda K, Imoto I, Kaji T, Yoshida Y, Nakayama S, Irahara M. Case of non-mosaic trisomy 20 in amniotic fluid cultures without anomalies in the fetus: cytogenetic discrepancy between amniocytes and fetal blood. J Obstet Gynaecol Res. 2015 Jan;41(1):141-4. doi: 10.1111/jog.12488. Epub 2014 Aug 28. PMID: 25164874.