Alpha-fetoprotein and acetylcholinesterase in twins discordant for neural tube defect |
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| Authors: | Virginia P Johnson MD Jaclyn Vidgoff Nancy Wilson Dean Madison |
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| Institution: | 1. Department of Genetics, Emanuel Hospital and Health Center, Portland, OR 97227, U.S.A.;2. Birth Defects Genetics Center, Departments of Obstetrics and Gynecology, Pediatrics and Laboratory Medicine, University of South Dakota School of Medicine, Vermillion, SD 57069, U.S.A. |
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| Abstract: | Twins concordant for elevated alpha-fetoprotein (AFP) and acetylcholinesterase (AChE) and discordant for neural tube defect (NTD) and sex are reported. A literature review reveals instances of termination of twin pregnancies with one normal and one abnormal fetus, partly based on concordant high AFP and positive AChE (although discordant on ultrasound examination). The levels of AFP and AChE in twin pregnancies are probably a function of the number of layers of fetal membranes separating twin sacs: dichorionic, diamniotic membranes allow transfer of AFP; monochorionic, diamniotic membranes allow transfer of both AFP and AChE. Cautious interpretation of biochemical findings and reliance on high resolution ultrasonography are suggested. |
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| Keywords: | Maternal serum alpha-fetoprotein Acetylcholinesterase Twins Neural tube defect Fetal membranes |
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