Protein in human sweat may protect some people against Lyme disease

A protein found in human sweat may offer protection from Lyme disease, a bacterial infection spread by ticks, research suggests.

For a new study, published March in the journal Nature Communications, scientists scoured huge datasets of human genetic information and compared the genes of people with and without Lyme disease. The researchers uncovered three genes associated with a higher risk of infection, two of which were known to be associated with the disease. However, the third gene — which makes a type of protein found in the skin and sweat — had never been tied to it.

This mutant gene carried by those with Lyme disease seemed to boost their susceptibility to the disease. But the researchers discovered that the standard, non-variant version of the gene can actually prevent the growth of Lyme disease-causing bacteria — at least in lab dishes and mice. About 60% of people are thought to carry the standard version of the gene, they noted.

Related: New anti-tick vaccine prevented Lyme disease (in guinea pigs)

This type of study, which sifts through a huge number of people's genomes for genes associated with a specific condition, had never been done for Lyme disease, co-senior author Michal Tal, a principal scientist at the Massachusetts Institute of Technology, told Live Science. They started with data from the FinnGen project, which contains genetic information from more than 410,000 Finnish people, including over 7,000 individuals diagnosed with Lyme disease.

That work revealed the mysterious variant of a gene that makes a protein called secretoglobin family 1D member 2 (SCGB1D2). Secretoglobins are small proteins secreted by cells, and in this case are found in sweat glands.

The researchers initially posted this discovery online in a preprint paper, and before long, they heard from a group in Estonia that had uncovered the same gene variant while examining data from the Estonian Biobank. The repository contains data from more than 210,000 Estonian people, including 18,000 with Lyme disease.