Clinical features of twins with adolescent idiopathic scoliosis

English Keywords:Adolescent idiopathic scoliosis  Monozygotic twins  Dizygotic twins  Genetics

English Abstract:

  【Abstract】 Objectives: To investigate the concordance for adolescent idiopathic scoliosis(AIS) in monozygotic and dizygotic twins, and to study the clinical features of monozygotic twins with AIS. Methods: From January 2007 to December 2016, twenty-one pairs(19 female pairs, 2 male pairs) of AIS twins were included from our spine center. The clinical and radiographical data were recorded at first visit including age, menarche, BMI, Cobb angle, thoracic kyphosis, lumbar lordosis and Risser sign, etc. Zygosity was determined by short tandem repeat analysis(STR). The concordance rate of AIS was compared between monozygotic and dizygotic twins. The two monozygotic twins in each pair were classified into severe group or mild group according to their severity of curve, and clinical data were compared between the two groups by using paired t-test. Results: The average age was 13.2±2.5 years, the mean Cobb angle was 29.2°±14.8°, thoracic kyphosis was 16.8°±9.2°, lumbar lordosis was 45.5°±7.4°, menarche age was 12.2±1.4 years, Risser sign was 2.3±1.6, BMI was 17.0±1.6kg/m2. Short tandem repeat analysis confirmed that 17 pairs were monozygotic and 4 pairs were dizygotic. For monozygotic twins, the concordance of AIS was 94.1%, 11 pairs(68.8%) had the similar curve patterns, the difference of Cobb angle between the two twins less than 10° was observed in 4 pairs(25.0%). For dizygotic twins, the concordance of AIS was 75.0%, 1 pair(33.3%) had the similar curve pattern, the difference of Cobb angle between the two twins less than 10° was observed in 1 pair(33.3%). Among the 12 pairs of monozygotic twins concordant for AIS with Cobb angle difference ≥10°, the severe group had younger age at menarche and lower BMI than the mild group(P<0.05). Conclusions: Monozygotic twins with AIS have higher concordance rate(94.1%) and curve pattern similarity, but lower curve severity similarity. The more severe one in the twins has smaller menarche age and lower BMI.