The study published in the journal Brain casts light upon the condition.
They also experience burns and other injuries without knowing. "Their nerves are all there, they're just not working how they should be".
A group of British scientists has finally decoded why six members of an Italian family can not feel pain even after suffering from burns and fractured bones.
The affected family members include a 78-year-old woman, her two middle-aged daughters, and their three children. Then, she continued saying that she had broken several bones, which she didn't correctly heal with medical assistance but let them harden by themselves.
But the family isn't interested: "I asked them if they would like to normally sense pain and they said no", Cox told the website.
"By identifying this mutation and clarifying that it contributes to the family's pain insensitivity, we have opened up a whole new route to drug discovery for pain relief", said Professor Anna Maria Aloisi from University of Siena in Italy.
An Italian family that is unable to feel pain are being studied by scientists in the hope that their shared disorder may lead to the development of new painkiller drugs.
The unique condition has been called Marsili syndrome after the family's surname, but is a form of congenital hypoalgesia. They believe that there are no other people in the world who is suffering from it.
A team led by researchers at University College London (UCL) in the United Kingdom identified the mutation that causes an Italian family, which includes six people, to have unusually low sensitivity to pain.
The mutation in the gene might help doctors to discover innovating pain-killer drugs.
After the rodents were given the family's mutated gene, they became much less sensitive to heat. They proceeded to experiment with mice to see if the finding could have any relation to the syndrome. The mutation seems to have this affect because the gene normally controls the activity of 16 other genes, some of which are involved in sensing pain. In this new study, the ZFHX2-altered mice had difficulty sensing hot and cold, offering further evidence that a mutation in the gene is what causes the family's lack of pain. Thus, also affecting the possibility of the brain to receive the messages. She often suffers burns because she doesn't feel any pain. Well, that's the case for six members of an Italian family who can't feel pain. On the other hand, some have never realized at the moment when they cut their tongues after bitting it.
Letizia believes she has a better life because she is not able to feel pain more than a few seconds.
Letizia Marsili, 52, first realised she was different when she was very young.
When the team deleted this gene entirely in mice, they found that the animals were not as good at sensing when painful pressure was applied to their tails, but they were hypersensitive to heat sensations.
The syndrome is very complex in the family.
Some of the relatives are unable to sweat while others barely do so.