21. Even the scientists are not sure precisely how the chimeraplasts bring about genetic changes . 22. Typically many such genetic changes are required before cancer develops. 23. By comparison, the viruses and bacteria used in vaccines make no long-term genetic changes . 24. Another genetic change softened the outer hull on the kernel. 25. Different genetic changes involving the " Gli3 " gene can cause Greig cephalopolysyndactyly syndrome. 26. His first task was to persuade his professor of the reality of genetic change . 27. Tumor suppressor genes are often disabled by cancer-promoting genetic changes . 28. "It's to make precise genetic changes in cells ." 29. He said these genetic changes clearly play a role in extending life in those animals. 30. Researchers are working to determine which genetic changes may influence the risk of atrial fibrillation.
