Multiple genes shape growth hormone response — from GHSR, which triggers GH pulses from the pituitary, to IGF1, which converts that signal into anabolic action, to ACTN3 and MSTN, which determine what the signal builds. The Precision Peptide Genetic Test analyzes all of them as part of 15 Muscle Growth insights across 14 pathways, 49 peptides, and 150+ genetic insights.