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Immunochemical studies of amniotic fluid: Decrease of a 36,000 polypeptide in pregnancies of fetuses with down´s syndrome

Débora D' A. Reis^I; Vânia F. Prado^I; Leila M. Farah^II; Sérgio D.J. Pena^I

^IDepartamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, UFMG, Caixa Postal 2486, 30161 Belo Horizonte, MG, Brasil. Send correspondence to S.D.J.P.
^IIDepartamento de Genética, Escola Paulista de Medicina, 04023 Sâo Paulo, SP

ABSTRACT

In a search for potential new biochemical markers for prenatal diagnosis of Down's Syndrome, we studied 14 samples of second trimester amniotic fluid obtained from pregnancies of fetuses with this chromosomal disease and an equal number of normal controls matched for gestational age. All samples were analyzed by one and two-dimensional Western Blots using an antiserum specific for the fetal proteins of human amniotic fluid. A fetal polypeptide with an apparent molecular weight of 36,000 (P36) was markedly decreased in ten (71%) of the Down's Syndrome amniotic fluids. Once appropriate quantitative immunoassays are developed, the deficiency of P36 may prove to be a useful biochemical marker for prenatal detection of Down's Syndrome.

Keywords: Immunochemical studies; Amniotic fluid; Polypeptide; Down's syndrome.

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