A 28-year-old white female and her 25-year-old white male partner present for genetic counseling. Both have one sibling with cystic fibrosis confirmed by sweat chloride testing (98 mEq/L). The couple is asymptomatic with normal pulmonary function tests and no personal history of pancreatic insufficiency. They desire preconception risk assessment for cystic fibrosis transmission to offspring. Which method most appropriately determines their carrier status and calculates recurrence risk?

1. A)Karyotype analysis
2. B)Biochemical testing
3. C)Western blot analysis
4. D)Polymerase chain reaction (PCR)GABARITO
5. E)Fluorescence in situ hybridization (FISH)