The chapter opener describes diagnosing Rett syndrome, which affects neurons in the brain, from DNA extracted from a saved baby tooth. Explain why a mutation detected in one cell type can be used to...

The chapter opener describes diagnosing Rett syndrome, which affects neurons in the brain, from DNA extracted from a saved baby tooth. Explain why a mutation detected in one cell type can be used to help diagnose an inherited condition that affects a different cell type.