The study included only two patients with the disorder, known as proopiomelanocortin deficiency.
But those two patients account for two-thirds of all known adult cases worldwide, said Dr. Marc Reitman, of the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.
The disorder is caused by mutations in the gene that makes the protein called proopiomelanocortin (POMC).
Normally, the POMC protein gets chopped into smaller proteins that affect different hormones in the body, explained Reitman, who wrote an editorial published with the study.
When the body lacks POMC, the adrenal glands (which churn out vital hormones) cannot work properly. If that adrenal insufficiency isn't recognized and treated quickly, the disease kills in infancy.