Methods of stratifying a subject having or at risk for developing adolescent idiopathic scoliosis (AIS) into diagnostically or clinically useful subclasses are provided. The stratification is based on the subjects Giα protein serine phosphorylation profile and/or the degree of imbalance in G-protein coupled receptor responses to Giα and Gsα protein stimulation. In some embodiments, the methods involve detecting or determining the level of serine phosphorylated Giα1 and/or Giα3 proteins in the cell sample, and/or determining a ratio between the response to Giα protein stimulation and the response to Gsα protein stimulation from a biological sample from the subject. Methods for predicting the risk of an AIS subject for developing a severe scoliosis, for predicting the subjects responsiveness to bracing treatment, and for identifying therapeutically useful compounds are also provided, as well as kits therefor.
