What is the easiest way to test for deleterious recessive genes?

• A. Phenotypic observation
• B. Pedigree analysis
• C. Random sampling
• D. DNA testing

Answer: (D)

Direct DNA testing of known mutations is the easiest way to detect deleterious recessive alleles. Carriers have one copy and typically show no symptoms, so you can’t rely on appearance to identify them. Testing the DNA directly reveals whether an individual has zero, one, or two copies of the harmful allele, allowing you to find both affected individuals (two copies) and carriers (one copy) even when they look normal. This makes it possible to make informed breeding choices to avoid producing affected offspring. Pedigree analysis can suggest who might carry based on inheritance patterns, but it can’t confirm carrier status for everyone, especially with incomplete data. Random sampling isn’t targeted to the specific mutations, and phenotypic observation misses carriers entirely, since they don’t express the deleterious trait.