Concordance Rates of Adolescent Idiopathic Scoliosis in a Danish Twin Population. Issue 19 (1st October 2016)

• Record Type: Journal Article
• Authors: Simony, Ane; Carreon, Leah Y.; H⊘jmark, Karen; Kyvik, Kirsten O.; Andersen, Mikkel Ø.
• Is Part Of: Spine. Volume 41:Issue 19(2016)
• Publication Date: 2016-10-01
• Subjects: concordance rate -- Danish Twin Registry -- scoliosis -- zygosity; Spine -- Abnormalities -- Periodicals; Spine -- Diseases -- Periodicals; Spine -- Surgery -- Periodicals; 616.73005
• DOI: 10.1097/BRS.0000000000001681
• Languages: English
• ISSNs: 0362-2436

Abstract

Abstract : Study Design: Clinical, radiological, and genetic determination of zygosity of twin pairs from the Danish Twin Registry who self-reported having adolescent idiopathic scoliosis (AIS). Objective: To establish concordance rates of AIS. Summary of Background Data: The etiology of and the true mode of inheritance of AIS remain unclear. Studies on concordance in twin pairs provide a basis for analyzing the influence of genetic versus environmental factors. In 2007, using self-report of AIS from the Danish Twin Registry, concordance rates of 0.13 in monozygotic twins and 0.00 in dizygotic twins were reported. Methods: All 46, 418 twins registered in the Danish Twin Registry born from 1931 to 1982 were sent a survey, which included questions about scoliosis. The survey was returned by 34, 944 individuals (75.3%) representing 23, 204 pairs. From the present study, 548 individuals representing 274 complete twin pairs in which at least one twin self-reported having scoliosis were invited to a clinical and radiological examination. Zygosity was established by genetic testing. Results: A total of 182 individuals (33.2%) of the original cohort agreed to participate, 128 of whom had scoliosis by self-report. There were 91 twin pairs, in which one or both twins had reported scoliosis and 36 individuals whose twin did not want to participate. Only 35 (27%) of the 128 participants with self-reported scoliosis had a clinically and radiologically confirmed curve. Calculating concordance in twins with Cobb angles greater than 10°, we found that the pairwise concordance rate was 0.4 (0.10–0.70) for monozygotic and 0.05 (−0.05–0.15) for dizygotic twins, P = 0.05, probandwise concordance was 0.45 (0.16–0.74) for monozygotic and 0.1 (−0.03–0.23) for dizygotic pairs. Conclusion: Concordance rates in a Danish twin population using genetic testing for zygosity are higher than previously reported using self-report. Although not statistically significant, the differences in monozygotic and dizygotic pairs indicate that genetic factors may be of importance for scoliosis. Level of Evidence: 3