A Controlled Trial of Growth Hormone in Phelan-McDermid Syndrome and Idiopathic Autism

Inclusion Criteria: * Children between 2 and 12 years of age * Open epiphyses on bone age x ray * Must be on stable medication and psychosocial treatment regimens for at least three months prior to enrollment, assuming the concomitant medication is safe for use with Growth Hormone * No prior use of Growth Hormone or IGF-1 * ASD group: Meet DSM-5 criteria for Autism Spectrum Disorder confirmed by the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2); absence of known pathogenic copy number variants * PMS group: Known pathogenic deletions or mutations in SHANK3 gene diagnosed by array CGH and/or direct sequencing Exclusion Criteria: * Closed epiphyses * Active or suspected neoplasia * Intracranial hypertension * Hepatic insufficiency * Renal insufficiency * Cardiomegaly/valvulopathy * History of allergy to growth hormone or any component of the formulation (mecasermin) * Patients with comorbid conditions who are deemed too medically compromised to tolerate the risk of experimental treatment with growth hormone (including severe obesity, sleep apnea, and various acute health conditions) * Visual problems that preclude the use of VEP