Lonapegsomatropin is a medication that is being tested to see how well it works for children and adolescents with growth failure or short stature. It is administered as an injection under the skin once a week.

Somatropin is a medication used as a comparison in this study. It is a growth hormone that is administered as a daily injection under the skin.

Short stature homeobox containing gene deficiency – This condition is caused by mutations in the SHOX gene, which is essential for bone growth. It typically leads to a reduction in height during childhood and adolescence. The deficiency affects the development of long bones in the arms and legs. This can result in shorter limbs compared to the rest of the body.

Turner syndrome – This is a genetic condition that occurs when one of the X chromosomes is partially or completely missing in females. It often results in shorter stature and distinct physical characteristics. The condition affects various aspects of physical development throughout the growing years.

Idiopathic short stature – This refers to a condition where a person is significantly shorter than average without an identifiable underlying medical cause. The growth rate is typically slower than expected for their age and sex. It is characterized by a lack of detectable hormonal or genetic abnormalities.

Small for gestational age – This describes infants whose birth weight, length, or head circumference are below the expected range for their gestational age. It is a condition identified at birth reflecting growth patterns during pregnancy. These individuals may continue to show different growth velocities during early childhood.