Embryo screening has been used successfully to screen for such diseases as cystic fibrosis and Tay-Sachs as well as for genes that predispose a person to breast or colon cancer. The procedure can also be used to determine the gender of the embryo. Given this ability, X-chromosome-linked diseases that manifest only in males (hemophilia, for example) can be
screened by implanting only female embryos (which will carry but will not develop the disease). Another variation that involves examining the sample to make sure it has the correct number of chromosomes is used for women over 35 (women past that age being statistically more likely to give birth to babies with Down syndrome and other chromosomal defects). Embryo screening has also been used to select a child who is a compatible donor for a sibling with a life-threatening disease such as certain anemias and leukemias.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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