Greater occurrence of schizophrenia in dizygotic but not monozygotic twins

1999 ◽  
Vol 175 (5) ◽  
pp. 407-409 ◽  
Author(s):  
Ulla Kläning
Keyword(s):  
General Population ◽  
Record Linkage ◽  
Monozygotic Twins ◽  
Young Cohort ◽  
Case Register ◽  
Dizygotic Twins ◽  
The Difference ◽  
Direction Opposite ◽  
First Admission ◽  
Danish Twin

BackgroundA previous study demonstrated a higher rate of first hospitalisation for schizophrenia in twins than in singletons.AimsTo compare the schizophrenia rates in monozygotic twins, dizygotic twins and the general population.MethodThrough record linkage between the Young Cohort of the Danish Twin Register and the Danish Psychiatric Case Register, the rate of schizophrenia in’ monozygotic and dizygotic twins and the rate in the general population were compared.ResultsThe rate of first admission to hospital for schizophrenia in dizygotic twins was 40% greater than that in the general population. The rate in monozygotic twins was not increased. The difference between the rates in mono- and dizygotic twins was statistically significant (P < 0.001)ConclusionsThis result is surprising and is in the direction opposite to that expected, suggesting new possibilities in the study of risk factors.

Increased Occurrence of Schizophrenia and other Psychiatric Illnesses Among Twins

1996 ◽  
Vol 168 (6) ◽  
pp. 688-692 ◽  
Author(s):  
Ulla Kläning ◽  
Preben Bo Mortensen ◽  
Kirsten Ohm Kyvik
Keyword(s):  
General Population ◽  
Psychiatric Disorders ◽  
Record Linkage ◽  
Admission Rate ◽  
Case Register ◽  
Psychiatric Illnesses ◽  
Increased Risk ◽  
Methodological Problems ◽  
First Admission ◽  
Danish Twin

BackgroundWe wished to establish whether the occurrence of schizophrenia among twins is the same as among the general population.MethodThrough record linkage between the New Danish Twin Register and the Danish Psychiatric Case Register, the twins who have ever received a diagnosis of schizophrenia were identified. Through indirect standardisation for age, sex and dates of admission, the rate of first admission with diagnosis schizophrenia among twins is compared to the same rate in the general population.ResultsA 28% increase in the rate of first admissions for schizophrenia in twins compared to the general population was found. This is statistically significant and does not seem to be caused by any known methodological problems. Twins also had an increased first-admission rate of any psychiatric disorders.ConclusionThis increased risk does not seem to be explained by known methodological problems, but does differ from earlier studies.

Winter-Born v Summer-Born Schizophrenics

1987 ◽  
Vol 151 (4) ◽  
pp. 499-505 ◽  
Author(s):  
R. E. Kendell ◽  
I. W. Kemp
Keyword(s):  
General Population ◽  
Health Service ◽  
Sex Ratio ◽  
Age Of Onset ◽  
Psychiatric Inpatient ◽  
Data Set ◽  
Case Register ◽  
Large Populations ◽  
To Receive ◽  
First Admission

Data from two sources-the Edinburgh Psychiatric Case Register and the psychiatric inpatient records of the Scottish Health Service-were used to compare large populations of first-admission schizophrenics born in winter (January to March) and in summer (June to October). Parallel comparisons were carried out for affective psychoses. Comparison of the months of birth of the Scottish patients with those of the general population indicated that there was a 9% excess of schizophrenic births and a 3% excess of affective births in the first 3 months of the year. In the Edinburgh material, winter-born schizophrenics were more likely than the summer-born to receive a diagnosis of paranoid or schizoaffective schizophrenia and less likely to receive diagnoses other than schizophrenia on readmission, but neither of these differences emerged in the much larger Scottish material. There were no differences between winter-and summer-born schizophrenics in age of onset, sex ratio, or prognosis in either data set, nor were any significant differences found between winter- and summer-born affectives. We have therefore failed to demonstrate any convincing differences between winter-and summer-born schizophrenics.

scholarly journals Lifespans of Twins: Does Zygosity Matter?

Genes ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 166 ◽  
Author(s):  
Jacob Hjelmborg ◽  
Pia Larsen ◽  
Jaakko Kaprio ◽  
Matt McGue ◽  
Thomas Scheike ◽  
...  
Keyword(s):  
Population Based ◽  
Dizygotic Twin ◽  
Vital Status ◽  
Age Cohorts ◽  
Mortality Process ◽  
Dizygotic Twins ◽  
Twin Registry ◽  
The Difference ◽  
Lifespan Distribution ◽  
Danish Twin

Studies with twins provide fundamental insights to lifespans of humans. We aim to clarify if monozygotic and dizygotic twin individuals differ in lifespan, that is, if zygosity matters. We investigate whether a possible difference in mortality after infancy between zygosities is stable in different age cohorts, and whether the difference remains when twins with unknown zygosity are taken into account. Further, we compare the distribution of long-livers, that is, the upper-tail of the lifespan distribution, between monozygotic and same-sex dizygotic twin individuals. The Danish Twin Registry provides a nationwide cohort of 109,303 twins born during 1870 to 1990 with valid vital status. Standard survival analysis is used to compare mortality in monozygotic and dizygotic twin individuals and twin individuals with unknown zygosity. The mortality of monozygotic and dizygotic twin individuals differs slightly after taking into consideration effects of birth- and age-cohorts, gender differences, and that twins are paired. However, no substantial nor systematic differences remain when taking twins with unknown zygosity into account. Further, the distribution of long-livers is very similar by zygosity, suggesting the same mortality process. The population-based and oldest twin cohort ever studied suggests that monozygotic and dizygotic twins have similar lifespans.

scholarly journals Twin studies of psychosis and the genetics of cerebral asymmetry

1999 ◽  
Vol 175 (5) ◽  
pp. 399-401 ◽  
Author(s):  
T. J. Crow
Keyword(s):  
General Population ◽  
Monozygotic Twins ◽  
Twin Studies ◽  
Weight Of Evidence ◽  
Perinatal Complications ◽  
Cerebral Asymmetry ◽  
Psychotic Illness ◽  
Dizygotic Twins ◽  
Increased Risk ◽  
Issue Reports

Kläning (1999, this issue) reports that dizygotic twins are at increased risk of schizophrenia relative to the general population. Any departure from the first assumption of twin studies that the illness has the same origin in twins as it does in the general population might tell us something about aetiology. Kläning's expectation that monozygotic twins would be at increased risk because such pairs are at increased risk of perinatal complications was not confirmed, adding to the weight of evidence that such complications are unrelated to the origins of psychotic illness. The contrary finding that dizygotic twins are at increased risk draws attention to the nature of dizygotic twinning. Is there something about this process that yields a clue to the origins of psychosis?

scholarly journals Genetic and environmental influences in Dupuytren’s disease: A study of 30,330 Danish twin pairs

2014 ◽  
Vol 40 (2) ◽  
pp. 171-176 ◽  
Author(s):  
S. Larsen ◽  
D. G. Krogsgaard ◽  
L. Aagaard Larsen ◽  
M. Iachina ◽  
A. Skytthe ◽  
...  
Keyword(s):  
Genetic Material ◽  
Monozygotic Twins ◽  
Dupuytren’S Disease ◽  
Level Of Evidence ◽  
Dupuytren's Disease ◽  
Relative Contribution ◽  
Dizygotic Twins ◽  
Genes And Environment ◽  
Hospital Registry ◽  
Danish Twin

We aimed to assess the relative contribution of genes and environment in the aetiology of Dupuytren’s disease by studying Danish twins born between 1870 and 2000. Twins with a diagnosis ( n = 365) and the subgroup who also had an operation ( n = 259) after 1977 were identified through linkage with a nationwide hospital registry among 30,330 monozygotic and same-sexed dizygotic twin pairs. Since monozygotic twins share all their genes and dizygotic twins share on average half of their genetic material, greater phenotypic similarity is expected in monozygotic than in dizygotic twins if a genetic component is involved. The number of concordant male twin pairs with Dupuytren’s disease was 17 and 7 (monozygotic and dizygotic pairs, respectively), compared with 60 and 174 discordant monozygotic and dizygotic pairs, yielding probandwise concordance rates of 0.37 (95% confidence interval (CI): 0.26 to 0.50) and 0.07 (95% CI: 0.04 to 0.14), respectively. The heritability of Dupuytren’s disease was approximately 80%. We conclude that genetic factors play a major role in the development of Dupuytren’s disease. Level of evidence: 3

scholarly journals Age-dependency in mortality of Finnish family caregivers: a nationwide register-based study

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
T M Mikkola ◽  
H Kautiainen ◽  
M Mänty ◽  
M B von Bonsdorff ◽  
T Kröger ◽  
...  
Keyword(s):  
General Population ◽  
Family Caregivers ◽  
Family Caregiver ◽  
Causes Of Death ◽  
Lower Mortality ◽  
All Cause Mortality ◽  
The Difference ◽  
Caregiver Role ◽  
Selection Of

Abstract Purpose Mortality appears to be lower in family caregivers than in the general population. However, there is lack of knowledge whether the difference in mortality between family caregivers and the general population is dependent on age. The purpose of this study was to analyze all-cause mortality in relation to age in family caregivers and to study their cause-specific mortality using data from multiple Finnish national registers. Methods The data included all individuals, who received family caregiver's allowance in Finland in 2012 (n = 42 256, mean age 67 years, 71% women) and a control population matched for age, sex, and municipality of residence (n = 83 618). Information on dates and causes of death between 2012 and 2017 were obtained from the Finnish Causes of Death Register. Flexible parametric survival modeling and competing risk regression adjusted for socioeconomic status were used. Results The total follow-up time was 717 877 person-years. Family caregivers had lower all-cause mortality than the controls over the follow-up (8.1% vs. 11.6%) both among women (hazard ratio [HR]: 0.64, 95% CI: 0.61-0.68) and men (HR: 0.73, 95% CI: 0.70-0.77). Younger adult caregivers had equal or only slightly lower mortality than their controls, but after age 60, the difference increased markedly resulting in over 10% lower mortality in favor of the caregivers in the oldest age groups. Caregivers had lower mortality for all the causes of death studied, namely cardiovascular, cancer, neurological, external, respiratory, gastrointestinal and dementia than the controls. Of these, the lowest was the risk for dementia (subhazard ratio=0.29, 95%CI: 0.25-0.34). Conclusions Older family caregivers have lower mortality than the age-matched controls from the general population while younger caregivers have similar mortality to their peers. This age-dependent advantage in mortality is likely to reflect selection of healthier individuals into the family caregiver role. Key messages The difference in mortality between family caregivers and the age-matched general population varies considerably with age. Advantage in mortality observed in family caregiver studies is likely to reflect the selection of healthier individuals into the caregiver role, which underestimates the adverse effects of caregiving.

scholarly journals Detection of New Translocation in Infant Twins with Concordant ALL and Discordant Outcome

2020 ◽  
Vol 13 (1) ◽  
pp. 9-14
Author(s):  
Golamreza Bahoush ◽  
Maryam Vafapour ◽  
Roxana Kariminejad
Keyword(s):  
Gene Rearrangement ◽  
Cytogenetic Study ◽  
Lymphoblastic Leukemia ◽  
Monozygotic Twins ◽  
Protective Role ◽  
Genetic Studies ◽  
Cytogenetic Testing ◽  
The Difference ◽  
Special Case ◽  
Mll Gene Rearrangement

About 2–5% of acute lymphoblastic leukemia (ALL) cases in pediatric patients are infants with an unfavorable prognosis because of high relapse probability. Early detection of the disease is, therefore, very important. Despite the fact that leukemia in twins occurs rarely, more attention has been paid to it in genetic studies. In the present study, through cytogenetic testing, a special case of concordant ALL in monozygotic twins was presented with different outcomes. In spite of an acceptable initial consequence to medical treatment in twins, in another brother (Twin B), early relapse was observed. In the cytogenetic study, both twins expressed t (4; 11) (q21; q23) while twin A expressed t (2; 7) (p10; q10). No cases have previously reported this mutation. Whether this translocation has a protective role for leukemia with mixed-lineage leukemia (MLL) gene rearrangement is still unclear. The difference in the translocation identified in the identical twins is also subject to further investigations.

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