The family that feels injury differently
Letizia Marsili and several relatives have an inherited condition that makes many painful injuries go largely unnoticed. It is not the same as being immune to harm: burns, fractures, and other damage can still occur. The danger is that pain, normally an alarm that prompts someone to stop, protect an injury, or seek help, may fail to sound.
The family’s condition drew scientific attention because it offered a rare chance to study how genes shape pain. Researchers found a change in ZFHX2, a gene involved in regulating the activity of other genes. The result points to a more complicated pathway than a single broken “pain switch.” The family’s altered pain response appears connected to changes in the activity of several genes involved in sensing and processing pain.
Why Nav1.7 is a separate lead
Nav1.7 is a sodium channel—a protein that helps nerve cells generate electrical signals. It is made using instructions from the SCN9A gene. Other people with certain SCN9A mutations can have profound congenital insensitivity to pain, which is why Nav1.7 has attracted interest as a possible drug target.
That is distinct from the Marsili family’s ZFHX2 finding. Both lines of research help explain how pain signals can be altered, but the family’s condition is not evidence that their Nav1.7 channel is switched off.
The challenge of copying a rare mutation
A drug that blocks a pain pathway might reduce suffering without the risks associated with opioids, but a genetic change present throughout the body is not automatically safe or straightforward to reproduce with a medicine. Pain also protects against unnoticed injury, and blocking one channel may not reproduce the broader effects of an inherited condition.
The practical lesson is stark: pain is not the injury itself, but it is one of the body’s most useful warnings. For the Marsilis, a broken bone can be real even when the usual alarm is faint or absent.
