Why Some People Don’t Sweat? Genetics Holds Surprising Answers

Hyperhidrosis is a set of conditions that impair the body’s ability to regulate body temperature through sweating. People with hyperhidrosis may sweat little or little at all, sometimes not on demand. This state may sometimes be severe. Anhidrosis can be precipitated by a variety of conditions including genetically inherited diseases, acquired conditions, nerve injuries, and drug adverse effects. Hence, establishing the reason for the person not sweating becomes essential in preventing crystallization into major health hazards like heatstroke.

Acquired Causes and Other Factors

The inability to sweat is not always congenital. According to the health portal Verywell Health, reduced or complete absence of sweating can be a consequence of a range of acquired conditions. Nerve damage (peripheral neuropathy), which often occurs due to diabetes or alcoholism, can interrupt signals from the brain to the sweat glands.

Skin diseases like psoriasis, burns, or the effects of radiation can physically damage or block the sweat glands. Also, certain medications, including some antipsychotics, antihistamines, and calcium channel blockers, can have reduced sweating as a side effect. Autoimmune diseases such as lupus and Sjögren’s syndrome are also associated with this condition. Even some forms of lung cancer can cause the absence of sweating on one side of the body.

Dangers and Diagnostic Procedures

The biggest danger of anhidrosis is overheating. When the body cannot cool itself, through evaporation of sweat, the body temperature rises to dangerous levels, thus may cause heat cramps, heat exhaustion, and worst of all, heatstroke. Heatstroke is when the patient’s body temperature goes above 39.4 °C; the skin is hot and red and not sweating at all; and one may even lose consciousness.

Diagnosis begins with an extensive medical history and a physical examination. To clearly establish diminished or absent sweating, the physician can apply different tests. One is the thermoregulatory sweat test during which whole-body sweating is assessed under controlled conditions, while the other is a quantitative sudomotor axon reflex test (QSART), which measures the function of nerves that innervate sweat glands on a small patch of skin.

Mutation of a Single Gene as a Cause

Science has revealed that mutation of a single gene could be responsible for the inability to sweat. Scientists from the University of California, San Francisco, and Stanford University reported that research carried out on a Pakistani family who had multiple children unable to sweat showed that their sweat glands appeared normal but simply did not work.

Analysis of genetic code showed that these children had a defect in the ITPR2 gene. The gene acts as a switch to tell sweat glands to start working, and the signal is carried through calcium. There is a tiny change, as if someone misspelled a single letter in the instructions, with the consequence that this switch does not function in this family. NBC News stated that the “point mutation” was sufficient to completely block sweating. Interestingly, the affected family members had no other health problems, suggesting that this gene functions exclusively in sweat glands.

Rare Hereditary Diseases

Besides specific mutations, the complete absence of sweating (anhidrosis) is a key symptom of several rare hereditary disorders. One of the most well-known is hypohidrotic ectodermal dysplasia (HED), a multisystem disorder which, according to the National Organization for Rare Disorders (NORD), primarily affects hair, teeth, nails, and sweat glands.

Individuals with HED have a partial or complete lack of sweat glands, causing heat intolerance and frequent episodes of elevated body temperature. Other symptoms include sparse and thin hair, missing teeth, and characteristic facial features. The condition is most often inherited as an X-linked recessive trait, which is why it is fully expressed only in males.

Treatment and Future

Treatment is aimed at addressing the underlying cause, if possible, and preventing complications. This includes avoiding physical activities in the heat, staying in air-conditioned spaces, wearing light clothing, and using water misters to cool the skin.

Although a cure for the condition itself does not yet exist, scientific discoveries provide hope for other cases. The research on the ITPR2 gene suggests that the development of a drug that blocks its protein could reduce sweat production. This could open the door to new therapies for the opposite problem—excessive sweating (hyperhidrosis), which affects about 2% of the population.