A 9-year-old girl and a 19-year-old girl have a surprising point in common: they both share an extremely rare genetic mutation that can shed light on what we often call “sixth sense” in humans; that is, proprioception, or consciousness of the body in space.
The study, developed by scientists at the National Institutes of Health in Bethesda, Maryland (USA) , involved two patients with a unique neurological disorder and suggests that a gene called PIEZO2 controls proprioception, a “sixth sense ”that describes the consciousness of one’s own body in space. This genetic mutation causes both patients to have movement problems (difficulties in walking, problems in the hips, fingers, deformities in the feet …) and other difficulties that they overcome thanks to their sight and other senses.
“Our study highlights the critical importance of PIEZO2 and the senses under its control in our daily lives. Understanding the role of this gene in the senses – such as touch – can provide clues to a variety of neurological disorders, ”explains Carsten G. Bonnemann, leader of the work that publishes The New England Journal of Medicine.
The mutation in the PIEZO2 gene appears to block the normal production or activity of proteins in your cells. PIEZO2 is what scientists call a mechanosensitive protein because it generates electrical nerve signals in response to changes in cell shape, for example when cells in the skin and neurons in the hand respond by pressing the hand against a table. Mouse experiments suggest that this gene is found in neurons that control touch and proprioception.
“ Our results suggest that these patients are blind to touch. The patient’s version of PIEZO2 may not work, so their neurons cannot detect tactile movements or even the extremities ”, clarifies Alexander T. Chesler.
The complementary examinations showed that the young patients lacked body awareness. If they were deprived of sight, the patients could not guess the direction in which their joints were being moved and they were also less sensitive to certain forms of contact. They couldn’t feel the vibrations of a fork or the brush of a brush on the palm of their hand. However, the patients could feel other forms of contact. They couldn’t physically feel the brush, Chesler explains, but they experienced something of an emotional reaction to its touch. Their brain activity appeared in a different region than the control subjects.
“What is remarkable about these patients is that their nervous system compensates for their lack of touch and knowledge of the body. It suggests that the nervous system may have several alternative pathways that we can take advantage of when designing new therapies (such as Gordon Syndrome or Marden-Walker Syndrome), ”says Bonnemann.
Similarly, the researchers speculate that different variants of the PIEZO2 gene could contribute to a person being clumsy, coordinated, or something in between.
