1. A method for diagnosing an increased risk for developing adolescent idiopathic scoliosis (AIS) in a human, comprising detecting the presence or absence of at least one impairment in melatonin-signaling pathway in at least one of the human's cells, wherein the cells are selected from the group consisting of blood cells, osteoblasts, osteoclasts and myoblasts, and wherein the presence of the at least one impairment in the melatonin-signaling pathway indicates that the human possesses an increased risk for developing AIS.