Chromosomal defects refer to problems or abnormalities in our genetic material, specifically in our chromosomes. These defects can cause various health issues or conditions due to errors in the structure or number of chromosomes. Full definition
With new advances in genetics and medical techniques it is possible to determine many chromosomal defects in embryo. (religion-online.org)
While we're on the topic of science, it's also important to remember that boy - girl twins are almost never identical, but fraternal — except in cases of a rare chromosomal defect. (businessinsider.com)
Thus prenatal diagnosis is never acceptable if the intention is to abort the pregnancy; therapeutic procedures are acceptable only if there is a direct benefit to the embryo, such as the healing of an illness stemming from a chromosomal defect; and all experimentation is wrong that is not directly related to the good of the particular embryo and carried out with the parents» knowledge and consent. (faith.org.uk)