PGT involves genetic testing of the embryo for chromosomes and or specific genetic disorders. Usually at the blastocyst stage, embryos are genetically tested by removing a few cells from the outside of each embryo. Embryos are frozen and the cells are sent to a specialized genetic laboratory for testing. Embryos can be tested for:
1. Chromosomes – Chromosome errors can occur randomly in any egg or sperm. Errors are more likely to occur in eggs and increase with a woman’s age. Even in women at age 35, approximately 50% of eggs are chromosomally abnormal. Errors can involve an entire chromosome or part of a chromosome.
2. Structural Abnormalities – Some women and woman carry chromosome abnormalities that may be passed along to their child. These are usually translocations and often lead to infertility, miscarriages, or an affected child.
3. Genetic Diseases: Some families may have a known genetic disease in family members. A man or a woman may have the disease or may carry an abnormal disease mutation. These include autosomal recessive diseases (both the egg and sperm must carry the mutation to cause the disease in a child), autosomal dominanat disease (if either the egg or sperm carries the mutation a child has a 50% chance of getting the disease), or X linked (usually passed along from the eggs of a woman who carrier the abnormal mutation).