Curve characteristics in monozygotic twins with adolescent idiopathic scoliosis: 3 new twin pairs and a review of the literature.

Most authors state that there is strong evidence for a genetic origin of adolescent idiopathic scoliosis (AIS). This conclusion is mainly based on the fact that the rate of concordance for AIS in monozygotic twins is significantly higher than that in dizygotic twins. However, it is of interest to determine whether all elements of scoliosis formation are genetically predetermined. If this were the case, there would perhaps be less place for closed treatment. We surveyed the literature for monozygotic twin pairs in which both members suffered from idiopathic scoliosis and added 3 pairs from our own patient group. The total group consisted of 32 twin pairs. We found that gender, direction of the convexity, the level of the apex and the kyphotic angle were determined more by genetic factors than the lateral Cobb angle of the scoliotic curve. This suggests that variations in the environment may affect the curve patterns in monozygotic twins.