Spine . 2007 Denmark. Andersen MO et al
Adolescent idiopathic scoliosis in twins: A population-based survey
A questionnaire-based identification of adolescent idiopathic scoliosis (AIS) patients in a twin cohort.
The purpose of this study was to establish a scoliosis twin cohort to provide data on the heritability of AIS.
SUMMARY OF BACKGROUND DATA:
The etiology of AIS is still unclear, and the true mode of inheritance has yet to be established. Concordance rates in monozygotic twins have been reported to be between 0.73 and 0.92, and in dizygotic twins between 0.36 and 0.63. Studies on concordance in twin pairs provide a basis for analyzing the influence of genetic versus environmental factors.
All 46,418 twins registered in the Danish Twin Registry born from 1931 to 1982 were sent a questionnaire, which included questions about scoliosis. A total of 34,944 (75.3%) representing 23,204 pairs returned the questionnaire.
A subgroup of 220 subjects considered to have AIS was identified, thus giving a prevalence of 1.05%. The concordant twin pairs were all monozygotic. Pairwise, the concordance rate was 0.13 for monozygotic and zero for dizygotic twin pairs; proband-wise concordance was 0.25 for monozygotic and zero for dizygotic pairs. The concordance of monozygotic and dizygotic pairs was significantly different (P < 0.05).
We have found evidence for a genetic etiology in AIS, but the risk of developing scoliosis in 1 twin whose other twin has scoliosis is smaller than believed up until now.
Dev Neurorehabil 2007 Weiss HR
Idiopathic scoliosis: how much of a genetic disorder? Report of five pairs of monozygotic twins
The role of genetic factors in the development of Adolescent Idiopathic Scoliosis (AIS) has been well documented; however, reports of the specific mode of genetic inheritance are inconclusive. These facts, combined with the phenotypic variability of this disorder, suggest that the genetic expression of idiopathic scoliosis may be dependent on multiple factors and genetic interactions. However, it seems questionable whether there is evidence for a genetic aetiology for adolescent idiopathic scoliosis, when in monozygotic twins there is no 100% concordance of the symptoms and prognosis.
Five pairs of monozygotic tested twins with the diagnosis of AIS were presented in the outpatient practice of the author. There was no history of scoliosis in any other member of the family.
Pair 1: Growth is still left in both girls, however prognosis is totally different. The progression factor of the first girl was 1.75 and so she has a risk of >65% for curve progression, Cobb angle 40. Progression factor of the second girl was 0.56 and so she has a risk of <5% for curve progression, Cobb angle 18. Pair 2: Both girls presented with Risser 4. Cobb angle was 55 degrees in one of the twins (progression factor: 3.1; risk for progression >95%) and 220 in the other (progression factor: 0.7; risk for progression <5%). Curve pattern was thoracic in the first, double major in the second girl. Pair 3: Two monozygotic tested boys with similar bad prognoses and similar curve pattern and similar degrees of curvature (90 and 100 degrees). Pair 4: Two not tested girls with similar benign prognoses and similar curve patterns (18 and 22 degrees). Pair 5: Two monozygotic tested girls with different prognoses and similar curve patterns (26 and 49 degrees).
Different curve patterns in two of the five pairs of twins as well as different prognoses can be discussed as phenotypic variability of AIS, however the findings from the other three pairs may be interpreted in the way that genetic factors play a role in the aetiology of AIS.
ReserchGate 2009 Kimberly L. Kesling
Scoliosis in twins. A meta-analysis of the literature and report of six cases
This study is a meta-analysis of the world's literature on adolescent idiopathic scoliosis in monozygotic and dizygotic twins. Additionally, six previously unreported cases of scoliosis in twins are presented.
To compare and contrast the concordance, severity, and curve patterns in monozygotic and dizygotic twins with adolescent idiopathic scoliosis in an attempt to document a genetic etiology and delineate inheritance patterns for adolescent idiopathic scoliosis.
There are numerous case reports of twins sets with adolescent idiopathic scoliosis. However, this data has not been previously analyzed as a single data base.
The literature was searched for cases of twins with adolescent idiopathic scoliosis, and six cases of patients treated by authors were added. One hundred cases of sets of twins were discovered, 68 of which had sufficient data for comparative analysis. Each set was evaluated for monozygosity, concordance of scoliosis, curve pattern, and severity of curve.
Thirty-seven sets of twins were monozygous, and 31 sets were dizygous. Concordance was 73% among monozygous twins and 36% among dizygous twins. The difference is statistically significant at P < 0.003. Curve severity could be compared in 20 sets of monozygous twins and 16 sets of dizygous twins. Among monozygous twins, there was a correlation coefficient of r = 0.399 (P < 0.126). Curve pattern comparison was not statistically significant.
Monozygous twins have a significantly higher rate of concordance than dizygous twins, and the curves in monozygous twins develop and progress together. Based on these data, there is strong evidence for a genetic etiology for adolescent idiopathic scoliosis.
2013 Eur Spine J スェーデン Anna Grauerr et al
Family history and its association to curve size and treatment in 1,463 patients with idiopathic scoliosis
To study family history in relation to curve severity, gender, age at diagnosis and treatment in idiopathic scoliosis.
A self-assessment questionnaire on family history of scoliosis was administered to 1,463 untreated, brace or surgically treated idiopathic scoliosis patients.
Out of the 1,463 patients, 51 % had one or more relatives with scoliosis. There was no significant difference between females and males, nor between juvenile and adolescent study participants in this respect (p = 0.939 and 0.110, respectively). There was a significant difference in maximum curve size between patients with one or more relatives with scoliosis (median 35°, interquartile range 25) and patients without any relative with scoliosis (median 32°, interquartile range 23) (p = 0.022). When stratifying patients according to treatment (observation, brace treatment or surgery), we found that it was more common to have a relative with scoliosis among the treated patients (p = 0.011). The OR for being treated was 1.32 (95% CI 1.06-1.64) when the patient had a relative with scoliosis, compared to not having.
Larger curve sizes were found in patients with a family history of scoliosis than in the ones without. No relation between family history and gender or between family history and age at onset of idiopathic scoliosis was found. Although the presence of a family history of scoliosis may not be a strong prognostic risk factor, it indicates that these patients are at higher risk of developing a more severe curve.
Genetics and pathogenesis of idiopathic scoliosis