Martha, a 25-year-old woman, has come for her first clinic visit at eight weeks of pregnancy. She has a 3- year-old son who is in good health at home. Her husband is 27 years old and in good health....

Martha, a 25-year-old woman, has come for her first clinic visit at eight weeks of pregnancy. She has a 3- year-old son who is in good health at home. Her husband is 27 years old and in good health. When reviewing the family history, she tells you that her sister has a 1-year-old son with CF. What could you tell Martha about the inheritance of CF and her chance to be a CF carrier? What genetic testing would be appropriate to discuss with Martha?