On April 12, Patrice Abela, 55, will embark on a major challenge: run the equivalent of 90 marathons in less than four months, following the route of the Tour de France 2022, from Copenhagen to Paris.

With the aim of "challenging the scientific community" and "raising awareness of the disease" from which his two daughters, aged 12 and 13, are suffering: congenital insensitivity to pain.

In its most severe form, this syndrome is characterized by the absence of painful sensation since birth.

"For the eldest, we realized it when she started to walk because she was leaving trails of blood behind her. It was quite impressive and she had no complaints," Patrice Abela told AFP. engineer in the region of Toulouse, in the south of France.

A first infection in the toe, followed by a second, leads them to consult various doctors, who end up making the diagnosis.

For their second daughter with the same syndrome, "we had the experience of the first", continues this father of four children.

The protective role of pain

More than the disease itself, it is its consequences that pose a problem.

"Due to repeated infections, my eldest daughter lost the first joint of each of her fingers; she also had to have a toe amputated," he describes.

Suffering from micro-fractures in the knee that damaged their joints, the two sisters, who spend about three months a year in the hospital, only move about on crutches or in wheelchairs.

"Hyperlaxes (extreme flexibility: editor's note), they can reproduce the same movement over and over," says their father.

"When they take their shower, they perceive hot and cold, but if it burns, they don't feel anything", he illustrates again.

The pain, they know it, but it is a "psychological pain" that it is, with serious repercussions in their daily life.

"Rare" - only a few thousand cases are listed in the world, about fifteen in France - this disease is no less "extremely serious", underlines Dr Didier Bouhassira, who practices at the Center for the evaluation and treatment of pain from the Ambroise-Paré hospital (AP-HP), in Boulogne-Billancourt, in the Paris region.

“Pain indeed plays a major physiological role in protecting us from the dangers of the environment,” he explains to AFP.

Gene mutations

In the most extreme cases, children will "mutilate their tongue or fingers during the first teething".

Then having "a whole bunch of accidents, burning yourself or continuing to walk on fractured limbs, which heal badly"...

If the pathology is detected early enough, "then they have to be taught what is innate in others: to protect themselves," he says.

But many situations remain very problematic: a simple appendicitis, which manifests itself by fever but also by severe pain, can for example turn into a generalized infection of the abdomen if it is not taken in time.

Described for the first time in the 1930s, insensitivity to pain is explained, according to several studies, by genetic mutations that prevent the development of pain receptors or obstruct their functioning.

In most cases, a child has a one in two chance of being affected if both parents are carriers of the genetic abnormality.

Other studies have shown that excessive production of endorphins - hormones with a powerful pain-relieving effect - in the brain could also be the cause.

If no treatment exists for this particularly debilitating disease, the identification of the anomalies that explain it has at least made it possible to identify the crucial role that certain molecules play in the face of pain, underlines Dr. Bouhassira.

But better understanding pain will undoubtedly "contribute to the development of new analgesics" to, paradoxically, benefit all those who feel it, he bets.

© 2022 AFP