This basket trial will enroll prepubertal children and adolescents with clinically diagnosed and genetically confirmed (if applicable) TS, SHOX-D, SGA, or ISS between ages of ≥2 and \<18 years with open growth plates. The purpose of the study is to see how well treatment with once-weekly lonapegsomatropin works compared to treatment with daily somatropin. Approximately 186 participants will be distributed equally (1:1), to receive either lonapegsomatropin for 2 years or somatropin for 1 year followed by lonapegsomatropin for 1 year. This trial will be conducted in the United States, France, Germany, Italy, Romania, Spain and South Korea.
Chronological age between ≥2 and <18 years, at start of screening.
Naïve to growth hormone and growth hormone promoting therapies.
Prepubertal.
Able to stand without assistance.
Advanced bone age X-ray by central reading defined as >20% above chronological age in months (Greulich 1959).
Closed epiphyses as defined as bone age of ≥14.0 years in females or ≥16.0 years in males.
Current clinical diagnosis of diabetic retinopathy
Untreated moderate or severe sleep apnea as determined by formal (local) read of an inpatient or at-home sleep study.