Trisomy 20 Support Group

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Unconfirmed T20M Cases

A substantial number of medical articles have been written over the past 25 years on the subject of Trisomy 20 Mosaicism.

This page provides a brief selection of abstracts (and also further below a comprehensive list of links via Pubmed ) of the vast majority of reported cases where post-natal testing failed to detect any chromosome abnormality in the fetus or liveborn child. As you read, it will, however, become clear that many were able to confirm T20M in extra-embryonic cells (e.g. amniotic fluid, cord, placenta).

A case of T20M confirmed post-natally as confined to amniotic fluid (amnion)

Prenatal Diagnosis 1987 May;7(4):Pages 273-6

Prenatal diagnosis of trisomy 20 mosaicism indicating an extra embryonic origin.
Baldinger S, Millard C, Schmeling D, Bendel RP

An additional case of amniotic fluid trisomy 20 mosaicism is presented. After careful counselling, the pregnancy continued and a phenotypically normal female was delivered. This case of amniocyte mosaicism establishes the source of aneuploid cell line as amnion. Since an extra-embryonic origin of the mosaicism has been confirmed, this should be carefully considered as a real possibility in counselling such families.

A case of T20M confirmed post-natally as confined to placenta (Confined Placental Mosaicism - CPM)

J Gynecol Obstet Biol Reprod (Paris) 1995;24(6):Pages 606-9

Intrauterine growth retardation associated with a mosaic trisomy 20 limited to the placenta. A case report.
Lacoste-Jugnet N, Depret-Mosser S, Vinatier D, Savary D, Dufour P, Lefebvre-Maunoury C, Monnier JC

When an amniocentesis was performed to determine fetal age, the karyotype was found to be a trisomy 20 mosaic, which could not be confirmed at birth on peripheral blood but which was confirmed at the cytogenetic examination of the placenta. Fetal growth impairment occurred. Mosaic trisomy in the placenta alone is known to affect fetal development. Normally, lethal, mosaic trisomy found during antenatal diagnosis in a viable fetus with no detectable malformation suggests an extra-embryo anomaly. The risk of spontaneous abortion and fetal growth retardation is however increased making strict ultrasound surveillance essential in these pregnancies.

Below find a comprehensive list of similar articles. Just click on the author's name to access the abstract via PubMed.

The articles in bold text include details of follow-up studies of children born after the detection of T20M at amniocentesis.

Author
Title Reference

Chen JH, Hsu TY, Ou CY, Chang LF, Chang SY, Soong YK. Prenatal diagnosis of trisomy 20 mosaicism by maternal serum screening for Down syndrome. Eur J Obstet Gynecol Reprod Biol. 1999 Oct;86(2):175-7.

Hayashi S, Miharu N, He H, Honda H, Samura O, Nakaoka Y, Ohama K. A phenotypically normal liveborn male after prenatal diagnosis of trisomy 20 mosaicism. J Obstet Gynaecol Res. 1997 Jun;23(3):301-5.

Bartels I, Franke U, Braulke I, Rauskolb R, Raab-Vetter M. Normal outcome of a pregnancy with mosaicism for double trisomy in amniotic fluid cells. Prenatal Diagnosis. 1997 Sep;17(9):877-8.

Mascarello JT, Jones MC, Catanzarite VA, Brown KH. Mosaic triple trisomy in amniocytes from a phenotypically and karyotypically normal fetus. Prenatal Diagnosis. 1994 Mar;14(3):163-5.

Rabineau D. Trisomy 20 mosaicism in amniotic cell culture. Genetic counselling during the prenatal diagnosis. Presse Med. 1991 Sep 14;20(28):1327-9. French.

Donnenfeld AE, Mennuti MT, Long WS, Bartolo RG. Trisomy 20 mosaicism in amniotic fluid culture. American Journal of Medical Genetics. 1987 May;27(1):235-6. No abstract available

Baldinger S, Millard C, Schmeling D, Bendel RP. Prenatal diagnosis of trisomy 20 mosaicism indicating an extra embryonic origin. Prenatal Diagnosis. 1987 May;7(4):273-6.

Tolmie JL, Ferguson-Smith ME, Gilmore D, Ferguson-Smith MA. Normal development in two six-year-old boys born after prenatal diagnosis of trisomy 20 mosaicism Prenatal Diagnosis. 1987 Oct;7(8):597-601.

Abuelo DN, Barsel-Bowers G, Zartler AS. Follow-up of infants with amniotic fluid trisomy 20 mosaicism. American Journal of Medical Genetics. 1986 Jul;24(3):475-81.

Grewal MS, Ridler MA, Barber JC. Further examples of trisomy-20 mosaicism in amniotic cell cultures Prenatal Diagnosis. 1985 Mar-Apr;5(2):159-62.

Nisani R, Chemke J, Rappaport S, Felsenburg T. Genetic counselling for trisomy 20 mosaicism in amniotic fluid cell cultures. Acta Obstet Gynecol Scand. 1984;63(3):273-5.

Bosze P, Laszlo J, Toth A. Trisomy 20 mosaicism in amniotic fluid cells. Prenatal Diagnosis. 1982 Jul;2(3):225-7.

Mascarello JT, Chadwick DL, Moyers TG. Trisomy 20 mosaicism in amniotic fluid cells. Lancet. 1980 May 17;1(8177):1089. No abstract available.

Weise W, Quent P. Importance of trisomy-20 mosaicism to prenatal diagnosis Zentralbl Gynakol. 1980;102(14):770-3. German.

Nevin NC, Nevin J, Thompson W. Trisomy 20 mosaicism in amniotic fluid cell culture. Clinical Genetics. 1979 May;15(5):441-3.

Kardon NB, Lieber E, Davis JG, Hsu LY. Prenatal diagnosis of trisomy 20 mosaicism. Clinical Genetics. 1979 Mar;15(3):267-72.

Rodriguez ML, Luthy D, Hall JG, Norwood TH, Hoehn H. Amniotic fluid cell mosaicism for presumptive trisomy 20. Clinical Genetics. 1978 Feb;13(2):164-8

Confirmed T20M Cases T20M Amnio Stories