Prader-Willi syndrome (PWS) is a rare and complex genetic condition. It is characterized by distinct phenotypical features, short stature and morbid obesity, growth hormone (GH) deficiency and hypogonadism. The purpose of this study (N=355 individuals) was to describe differences in PWS phenotypic features by gender, molecular PWS subtype (deletion vs. UPD), and the use of GH and sex hormone (SH) treatments.
Hypotheses include 1) Individuals with deletion versus UPD have an increased frequency and more severe features, 2) Individuals treated with GH or SH have normalization of features, 3) The age at the GH or SH treatment initiation impacts the effects of treatment.
Individuals with deletions were found to have more frequent incidence of features such as: flat occiput, strabismus, almond shaped eyes, etc. They also tend to be heavier and with smaller head circumferences.
Individuals who were treated with GH had lower incidences of some phenotypic features such as: prominent occiput, almond shaped eyes, exotropia, etc. This study has also confirmed that PWS individuals who were treated with GH on average are taller, with lower BMIs, and longer hands and feet. Initiating GH treatment below the age 4 years also demonstrated lower incidence rate of phenotypic features such as micrognathia, slit-like eyes, abdominal fat distribution, etc.
The effect of the SH treatment is less obvious and requires further investigation.
The results of this study support the benefit of GH treatment for individuals diagnosed with PWS and supports the benefits of starting the GH treatment at a younger age.