A recent study of mice might explain why women with endometriosis may be underweight. The results indicate a low body mass index (BMI) could be induced by metabolic dysregulation in certain liver genes, which would establish endometriosis as a metabolic, systemic and multiorgan disease.

The study “Low body mass index in endometriosis is promoted by hepatic metabolic gene dysregulation in mice,” was published in Biology of Reproduction.

Endometriosis, characterized by the formation of proliferated endometrial cells outside the uterine cavity, is considered one of the most common gynecological disorders experienced by reproductive-aged women, negatively impacting their quality of life.

The exact causes of endometriosis are still not fully understood, but growing evidence points to genetic dysregulation. It is well established that the major point of metabolic regulation lies in the liver. In obese women, alteration in expression of certain liver genes has been demonstrated. But in women with endometriosis, modification in liver gene expression has not been investigated.

Researchers in this study speculate that endometriosis could affect the expression of the liver genes, which in turn, would lead to lower BMI. To verify their hypothesis, they artificially induced endometriosis in female mice, which then were weighed weekly and weight changes were compared over time.

The results suggested that, compared to control subjects, the mice with endometriosis had less body weight and total body fat. Overall, the liver function was normal except for differences noticed in the metabolic genes. Genetic analysis of the liver in the mice with endometriosis revealed a total of 26 genes that were differently regulated. Four of these genes were linked to weight loss and found to increase in expression. Two other genes among the 26 genes were associated with obesity and found to be reduced in expression. The researchers believe these features are specific to metabolic pathways.

“In summary, we demonstrate that endometriosis leads to a decreased body weight and the disruption of hepatic gene expression. The effect selectively targets a limited number of genes associated with metabolism. These alterations to liver metabolism likely contribute to the low BMI observed in women with endometriosis, demonstrating a previously unknown metabolic component to this disease,” the authors concluded.