Introduction Genetic factors are considered to play a significant role in adolescent idiopathic scoliosis (AIS). We previously developed a polygenic risk score (PRS) to predict the risk for the development and progression AIS utilizing the world's largest genome-wide association study (GWAS) dataset. However, no studies have investigated the relationship between PRS and the spinal morphology of AIS. This study aims to elucidate how PRS influences the morphological characteristics of AIS.

Methods A total of 106 female AIS patients who underwent GWAS were included in this study. The AIS susceptibility PRS was calculated using a previously conducted GWAS cohort (Case = 3,028; Control = 28,971). The correlation analyses were conducted between PRS and various parameters including body mass index (BMI), bone mineral density (BMD), Cobb angles (proximal thoracic (PT_Cobb), main thoracic (MT_Cobb), thoracolumbar (TL_Cobb)), main curve flexibility, sagittal spinal alignment (TK, SS, PT, PI, LL, PI-LL mismatch), apical vertebral rotation, vertebral wedging (concave/convex vertebral height), and pedicle length and diameters on computed tomography (CT).

Results No significant correlation was observed between PRS and BMI or BMD. While PRS showed no significant correlation with PT_Cobb or TL_Cobb angles, a significant positive correlation with MT_Cobb angle was found (r = 0.34, p = 0.003), and a significant negative correlation was observed with main curve flexibility (r = -0.21, p = 0.03). Stratified analysis by curve type revealed that a significant positive correlation between PRS and MT_Cobb angle (r = 0.34, p = 0.003), and a significant negative correlation between PRS and vertebral wedging (r = -0.24, p = 0.047) in the thoracic curve group, whereas no correlation was observed in the lumbar curve group. Partial correlation analysis adjusted for MT_Cobb revealed no significant association between PRS and vertebral wedging.

Conclusion This study demonstrated that higher PRS was associated with increased Cobb angle in the main thoracic curve and reduced flexibility in AIS. However, no significant associations were found between PRS and spinal morphology on CT imaging. These findings suggest that genetic predisposition may contribute to curve progression through mechanisms beyond bone stracture, such as cartilage, nerves, and muscles. Understanding these genetic influences provides new insights into AIS pathogenesis.