Read this news story from the journal Nature on a genetic mutation that eliminates the ability to feel pain.

• How did scientists know that this was a genetic disorder?
• What gene is involved in this condition, and why how does a mutation in this gene prevent the sensation of pain?
• Why does this altered protein prevent pain sensation but not the sensation of touch, temperature, sight, or any other modality except pain? How is that possible?
• Based on the mechanism of this disease, would you expect the mutant allele to be recessive or dominant?
• Are the people affected by this mutation free of all types of pain?