Age- and Sex-differences in the Validity of Questionnaire-based Zygosity in Twins

Christiansen, Lene; Frederiksen, Henrik; Schousboe, Karoline; Skytthe, Axel; Wurmb‐Schwark, Nicole von; Christensen, Kaare; Kyvik, Kirsten Ohm

doi:10.1375/136905203322296610

Cited by 245 publications

(201 citation statements)

References 13 publications

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“…Zygosity was ascertained by the twins and their parents' reporting of physical similarity. Both twin and parental ratings of zygosity have been previously validated against DNA markers [9,11,12]. We have also used a questionnaire with acceptable validity and reliability to evaluate LBP.…”

Section: Discussionmentioning

confidence: 99%

Genetic and environmental influences on non-specific low back pain in children: a twin study

et al. 2008

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Aggregation of low back symptoms in families of children with low back pain (LBP) has been described. However, this may be due to genetic factors or common exposure to environmental factors. The aim of this study was to evaluate the relative contribution of genetic and environmental factors to childhood LBP by comparing the pairwise similarity of LBP in pairs of monozygotic (MZ) and dizygotic (DZ) twin children. Data was collected from 1995 to 1998 from a national sample of Finnish 11-year-old twins born between 1984 and 1987. This study sample constituted of 1,790 twin pairs: 610 MZ pairs, 598 same-sex DZ pairs, 582 opposite-sex DZ pairs. LBP pain was determined by using a validated pain questionnaire designed to assess musculoskeletal pains during the preceding 3 months. The outcome measure, LBP, was considered in three categories: none, once a month and at least once a week. Twin similarity in the report of LBP was quantified by correlations. Variance components for genetic and environmental factors were estimated by using biometric structural equation modelling techniques. The prevalence of LBP at least once a month was 15.7%, and at least once a week was 6.6%. The prevalence of frequent LBP in boys was significantly higher than that in girls (P = 0.04). In both genders, there were no differences in LBP reporting by zygosity (P [ 0.2). There were no statistically significant differences between polychoric correlations in male MZ and DZ pairs and between polychoric correlations in female MZ and DZ pairs, suggesting little genetic influence. Results obtained from the best-fitting genetic model suggests that, of the total variance in LBP, 41% (95% CI 34-48) could be attributed to shared environmental factors within families; and 59% (52-66) to unique (unshared) environmental factors. Our results suggest that genetic factors play, at most, a minor role in LBP in children; instead, symptoms seem to be related to a mixture of shared and unshared environmental factors. This study underscore the need for further highquality research, preferably prospective studies, to identify important modifiable risk factors in order to guide interventions that may prevent LBP in childhood.

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Section: Discussionmentioning

confidence: 99%

Genetic and environmental influences on non-specific low back pain in children: a twin study

et al. 2008

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“…Zygosity was determined using similarity questions, a method which has been shown to provide at least 95% agreement with blood typing (Martin & Martin, 1975;Christensen et al, 2003). In both samples, women are slightly overrepresented.…”

Section: Methodsmentioning

confidence: 99%

Heritability in Political Interest and Efficacy across Cultures: Denmark and the United States

et al. 2012

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Interest in politics is important for a host of political behaviors and beliefs. Yet little is known about where political interest comes from. Most studies exploring the source of political interest focus on parental influences, economic status, and opportunity. Here, we investigate an alternative source: genetic transmission. Using two twin samples, one drawn from Denmark and the other from USA, we find that there is a high degree of heritability in political interest. Furthermore, we show that interest in politics and political efficacy share the same underlying, latent genetic factor. These findings add to the growing body of literature that documents political behaviors and attitudes as not simply the result of socialization, but also as part of an individual's genetically informed disposition.

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“…Zygosity Zygosity of the twins in the Danish Twin Registry had previously been assigned on the basis of physical resemblance, which provided >95% accuracy of classification [12], but zygosity of those included in the study was confirmed using 12 highly polymorphic microsatellite markers. Identity in all markers indicated >0.99 probability of monozygosity.…”

Section: Methodsmentioning

confidence: 99%

Adult glucose metabolism in extremely birthweight-discordant monozygotic twins

et al. 2012

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Aims/hypothesis Low birthweight (BW) is associated with increased risk of type 2 diabetes. We compared glucose metabolism in adult BW-discordant monozygotic (MZ) twins, thereby controlling for genetic factors and rearing environment. Methods Among 77,885 twins in the Danish Twin Registry, 155 of the most BW-discordant MZ twin pairs (median BW difference 0.5 kg) were assessed using a 2 h oral glucose tolerance test with sampling of plasma (p-)glucose, insulin, C-peptide, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1. HOMA for beta cell function (HOMA-β) and insulin resistance (HOMA-IR), and also insulin sensitivity index (BIGTT-SI) and acute insulin response (BIGTT-AIR), were calculated. Subgroup analyses were performed in those with: (1) double verification of BW difference; (2) difference in BW >0.5 kg; and (3) no overt metabolic disease (type 2 diabetes, hyperlipidaemia or thyroid disease).Results No intra-pair differences in p-glucose, insulin, C-peptide, incretin hormones, HOMA-β, HOMA-IR or BIGTT-SI were identified. p-Glucose at 120 min was higher in the twins with the highest BW without metabolic disease, and BIGTT-AIR was higher in those with the highest BW although not in pairs with a BW difference of >0.5 kg. Conclusions/interpretation BW-discordant MZ twins provide no evidence for a detrimental effect of low BW on glucose metabolism in adulthood once genetic factors and rearing environment are controlled for.

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Age- and Sex-differences in the Validity of Questionnaire-based Zygosity in Twins

Cited by 245 publications

References 13 publications

Genetic and environmental influences on non-specific low back pain in children: a twin study

Genetic and environmental influences on non-specific low back pain in children: a twin study

Heritability in Political Interest and Efficacy across Cultures: Denmark and the United States

Adult glucose metabolism in extremely birthweight-discordant monozygotic twins

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