IPLab:Lab 5:Trisomy 21

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Clinical Summary

This 44-year-old woman was 12 weeks pregnant with her third child when routine blood work showed a maternal serum alpha-fetoproteinAlpha-fetoprotein (AFP) is a serum glycoprotein produced during pregnancy by the yolk sac, fetal GI tract, and fetal liver. Elevated serum AFP levels in a pregnant woman can be an indication of a fetal neural tube defect (or something as common as multiple pregnancy). Open fetal neural tube defects allow alpha-fetoprotein to leak into the amniotic fluid, from which it crosses the placenta and enters the maternal bloodstream. Elevated maternal AFP is an indication for amniocentesis (of which an AFP level of amniotic fluid is routine) and an ultrasound. The combination of these two tests are very reliable in detecting neural tube defects.Alpha-fetoprotein (AFP) is a serum glycoprotein produced during pregnancy by the yolk sac, fetal GI tract, and fetal liver. Elevated serum AFP levels in a pregnant woman can be an indication of a fetal neural tube defect (or something as common as multiple pregnancy). Decreased serum levels are indicative of trisomy 21. level that was lower than expected for her stage of pregnancy. At 15-weeks of gestation she underwent ultrasound-guided amniocentesisAmniocentesis is a procedure in which a needle is inserted transabdominally through the uterus, into the amniotic sac, and amniotic fluid is withdrawn. and samples of the fluid containing cells were smeared onto glass slides for fluorescent in situ hybridizationFISH uses a fluorescent-labeled antibody specific for a particular chromosome. (FISH). The remainder of the sample was spun down and the fluid was sent for analysis and the cells were cultured for karyotyping.

Findings

FISH demonstrated three copies of chromosome 21. The patient was informed of these results and was told that definitive results from the karyotyping studies would take several days. The patient was referred to a medical geneticist for counseling.

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Study Questions


Additional Resources

Reference

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