There are different types of concerns that can arise when performing genetic testing; to use an analogy, there could be large paragraphs of text that accidentally repeat themselves, which alters the meaning of a chapter in a book, or there could be single letter changes in important sentences that change the meaning of an important thought. Our geneticist, Dr. Tamar Goldwaser, talks today about those latter changes: single gene mutations, and how we are able to detect them during pregnancy.