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| 12. |
- Jansson, M, et al.
(författare)
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Gender differences in heritability of depressive symptoms in the elderly
- 2004
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Ingår i: PSYCHOLOGICAL MEDICINE. - 0033-2917 .- 1469-8978. ; 34:3, s. 471-479
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The present study aimed to investigate the relative importance of genetic and environmental influences on depressive symptoms in the elderly. METHOD: Depressive symptoms were assessed through the Center for Epidemiological Studies-Depression (CES-D) scale. The CES-D scale was administered to 959 twin pairs (123 female MZs, 90 male MZs, 207 same-sex female DZs, 109 same-sex male DZs and 430 opposite-sex DZs) aged 50 years or older (mean age 72 years). A dichotomous depressed state variable was constructed based on CES-D cut-offs and self-reported use of antidepressant medication. Structural equation models were fitted to the data to dissect genetic and environmental variance components. RESULTS: The sex-specific heritability estimates for depressive symptoms were 14% for males and 29% for females and 23% when constrained to be equal for men and women. The prevalence of clinically significant depressive symptoms was 16% for men and 24% for women. Heritability estimates for the dichotomous depressed state measure were 7% for males and 49% for females in the full model and 33% when constrained to be equal. CONCLUSION: Our results suggest that depressive symptoms in the elderly are moderately heritable, with a higher heritability for women than men, although differences in heritability estimates were not statistically significant.
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| 13. |
- Johansson, Annica, 1969, et al.
(författare)
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Variants of CYP46A1 may interact with age and APOE to influence CSF Abeta42 levels in Alzheimer's disease.
- 2004
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Ingår i: Human genetics. - : Springer Science and Business Media LLC. - 0340-6717 .- 1432-1203. ; 114:6, s. 581-7
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have suggested that variants of CYP46A1, encoding cholesterol 24-hydroxylase (CYP46), confer risk for Alzheimer's disease (AD), a prospect substantiated by evidence of genetic association from several quantitative traits related to AD pathology, including cerebrospinal fluid (CSF) levels of the 42 amino-acid cleavage product of beta-amyloid (Abeta42) and the tau protein. In the present study, these claims have been explored by the genotyping of previously associated markers in CYP46A1 in three independent northern European case-control series encompassing 1323 individuals and including approximately 400 patients with measurements of CSF Abeta42 and phospho-tau protein levels. Tests of association in case-control models revealed limited evidence that CYP46A1 variants contributed to AD risk across these samples. However, models testing for potential effects upon CSF measures suggested a possible interaction of an intronic marker (rs754203) with age and APOE genotype. In stratified analyses, significant effects were evident that were restricted to elderly APOE epsilon4 carriers for both CSF Abeta42 ( P=0.0009) and phospho-tau ( P=0.046). Computational analyses indicate that the rs754203 marker probably does not impact the binding of regulatory factors, suggesting that other polymorphic sites underlie the observed associations. Our results provide an important independent replication of previous findings, supporting the existence of CYP46A1 sequence variants that contribute to variability in beta-amyloid metabolism.
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| 18. |
- Larsson, Mats, et al.
(författare)
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Genetic correlations among texture characteristics in the human iris
- 2004
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Ingår i: Molecular Vision. - 1090-0535. ; 10, s. 821-831
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:To estimate the magnitude of genetic correlations among five general textural characteristics of the human iris.METHODS:Color photographs of iris were available from 100 monozygotic and 99 dizygotic twin pairs. Comparative scales were constructed based on ratings of the subjects' left iris. To explore the genetic and environmental covariation among frequency of Fuchs' crypts, frequency of pigment dots, iris color, the extension, and distinction of Wolfflin nodules, and contraction furrows, a structural equation model with Cholesky decomposition was applied to variance-covariance matrices for monozygotic (MZ) and dizygotic (DZ) pairs.RESULTS:Significant genetic correlations fell between -0.22 and 0.44 and accounted almost entirely for the phenotypic correlations among the iris characteristics. No evidence for individual specific environmental effects in common to the characteristics was found.CONCLUSIONS:The modest genetic correlations indicate that there is little overlap in the genetic influence for these characteristics. Candidate genes with embryological and histological expression patterns in the eye could potentially influence the iris characteristics' variability.
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| 19. |
- Larsson, Mats, et al.
(författare)
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Importance of genetic effects for characteristics of the human iris
- 2003
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Ingår i: Twin research. - : Cambridge University Press (CUP). - 1369-0523 .- 2053-6003 .- 0000-0000. ; 6:3, s. 192-200
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Tidskriftsartikel (refereegranskat)abstract
- The relative importance of genetic influences (heritability) on five general textural quality characteristics of the human iris was assessed using sex and age limitation models. Colour photographs of irises were available from 100 monozygotic twin pairs, 99 dizygotic twin pairs, and 99 unrelated randomly paired age-matched German subjects. Comparative scales were constructed and two judges who were blind to zygosity independently rated five characteristic of the subjects' left iris. Inter-rater reliabilities were larger than .90 for all five scales. The heritabilities for the five iris characteristics ranged from .51-.90. No sex-specific genetic factors were found for the iris characteristics. Age-group differences in heritability were found for one of the five iris characteristics — "distinction of white dot rings". Heritability was greater for the older cohort (90%) than the younger (73%). The iris characteristics that showed the next highest additive-genetic effect were "contractional furrows" (78%) and "frequency of crypts" in the main stroma leaf (66%).
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| 20. |
- Lichtenstein, Paul, et al.
(författare)
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Remembered Parental Bonding in Adult Twins: Genetic and Environmental Influences
- 2003
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Ingår i: Behavior Genetics. - 0001-8244. ; 33:4, s. 397-408
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Tidskriftsartikel (refereegranskat)abstract
- One common assumption in psychology is the impact of parenting and parent-child relationships on the child's adjustment throughout the life span. Studies have indicated that there are genetic influences on memories of parenting, but how these influences are mediated has not typically been investigated. A sample of 150 pairs of monozygotic and 176 pairs of dizygotic Swedish twin women reported on personal characteristics and on remembered relationships with their mother and father using the Parental Bonding Instrument (PBI). Quantitative genetic analyses showed moderate genetic influences for remembered parental warmth, which also was partly explained by genetic influences for optimism, aggression, and humor. The other two PBI scales, authoritarianism and protectiveness, showed only shared and nonshared environmental influences. One interpretation of the findings is that heritable personal characteristics of children elicit parental warmth. However, other explanations such as personality characteristics influencing how experiences with parents are interpreted or circumstances in adult life that affect the recall of experiences could not be ruled out.
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