A study reports that a DNA variant is associated with increased disease risk. A second study finds the variant in many healthy adults.
Which statement best explains why these findings do not necessarily conflict?
Healthy adults cannot carry variants associated with any disease.
An association means that the variant always causes the disease.
The variant must have been produced by treatment of the disease.
A variant can increase risk without being sufficient to cause disease.
40 exam-style questions on Edexcel GCSE Biology 3.4 Variation and the Human Genome Project, covering 3.4.1 Causes of variation, 3.4.2 Outcomes of the Human Genome Project, 3.4.3 Genetic variation within a population, and 3.4.4 Effects of genetic mutations on phenotype. Each one has a worked solution and a mark scheme showing where the marks go.