A leading genetic cause of short stature in an Arab population

Human height is a trait that runs in families, yet for centuries, the full story of why some people grow tall and others remain short has remained incomplete. While scientists know that thousands of tiny genetic differences combine to shape a person's stature, a significant portion of this mystery has gone unsolved, particularly for populations that have been left out of large genetic studies. In many parts of the world, especially in the Middle East, families often share close genetic ties, which can sometimes concentrate specific genetic changes. When these changes affect growth, they can lead to short stature, a common reason for children to see a doctor. Understanding the specific genetic causes in these communities is not just about solving a medical puzzle; it is about finding treatments that work and ensuring that every child has the chance to reach their full potential.

A team of researchers has now uncovered a major piece of this puzzle, focusing on a large group of families in the United Arab Emirates. By studying the DNA of nearly five thousand children with rare medical conditions, they discovered that a single, specific change in a gene called GHSR is a leading cause of short stature in this population. This gene provides instructions for making a receptor, which acts like a docking station on the surface of cells in the brain and pituitary gland. Its job is to listen for a hormone called ghrelin, which signals the body to release growth hormone. Without a properly functioning receptor, the body misses the signal to grow, resulting in children who are significantly shorter than average.

The researchers found that this specific genetic change is surprisingly common among Emirati children referred for short stature, explaining 10.2% of all Emirati short stature referrals. In contrast, it is extremely rare in the general population and was almost entirely absent in healthy adults from the same region. The data suggests that this change originated from a single ancestor who lived in the northern part of the UAE roughly seventeen hundred years ago. Because of the way families in the region are structured, with many marriages between relatives, this genetic change has been passed down through generations, becoming concentrated in specific communities. The study showed that children who inherited two copies of this change, one from each parent, were the most severely affected, with a median height standard deviation score of -3.0. However, even children with just one copy of the change were often shorter than their peers, though to a lesser degree.

To understand exactly how this change stops growth, the scientists looked at the structure of the receptor protein and tested its function in the lab. They found that the change, which swaps one building block of the protein for another, breaks the receptor's ability to send signals. Even though the receptor sits correctly on the cell surface, it cannot communicate with the cell's internal machinery when the ghrelin hormone arrives. In experiments using microscopic worms, the researchers created a version of the worm with the same broken receptor. These worms grew to be noticeably smaller than their normal counterparts, confirming that the loss of this specific signal directly leads to reduced size. The study also showed that the severity of the short stature is influenced by the child's overall genetic background; children with a genetic makeup that naturally favors taller height were sometimes able to offset the effects of the broken receptor, while those with a background favoring shorter height were more severely impacted.

Despite the broken signal, the children's bodies still respond to treatment. When the researchers reviewed the medical records of patients who received growth hormone therapy, they found that the treatment worked well. The children grew at a healthy rate, and their levels of growth-related proteins in the blood increased significantly. This is a crucial finding because it means that even though the body's natural signal to grow is broken, doctors can bypass the problem by providing the growth hormone directly. The study also ruled out other potential causes, such as a common variation in a different growth-related gene, showing that the effect of this specific receptor change was the primary driver of the short stature in these families.

By identifying this single genetic cause, the researchers have provided a clear path forward for diagnosis and care. They recommend that genetic testing for this specific change become a standard part of the evaluation for any child with short stature in this population. This approach allows doctors to move quickly from uncertainty to a confirmed diagnosis, ensuring that families receive the right treatment without delay. The discovery highlights how studying specific populations can reveal hidden genetic factors that affect everyone, offering a clearer picture of human biology and a more effective way to help children grow.