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. 2017 Apr:18:320-326.
doi: 10.1016/j.ebiom.2017.04.002. Epub 2017 Apr 6.

Is an Early Age at Illness Onset in Schizophrenia Associated With Increased Genetic Susceptibility? Analysis of Data From the Nationwide Danish Twin Register

Rikke Hilker  1 , Dorte Helenius  2 , Birgitte Fagerlund  3 , Axel Skytthe  4 , Kaare Christensen  4 , Thomas M Werge  5 , Merete Nordentoft  6 , Birte Glenthøj  7
Affiliations

Is an Early Age at Illness Onset in Schizophrenia Associated With Increased Genetic Susceptibility? Analysis of Data From the Nationwide Danish Twin Register

Rikke Hilker et al. EBioMedicine. 2017 Apr.

Abstract

Background: Early age at illness onset has been viewed as an important liability marker for schizophrenia, which may be associated with an increased genetic vulnerability. A twin approach can be valuable, because it allows for the investigation of specific illness markers in individuals with a shared genetic background.

Methods: We linked nationwide registers to identify a cohort of twin pairs born in Denmark from 1951 to 2000 (N=31,524 pairs), where one or both twins had a diagnosis in the schizophrenia spectrum. We defined two groups consisting of; N=788 twin pairs (affected with schizophrenia spectrum) and a subsample of N=448 (affected with schizophrenia). Survival analysis was applied to investigate the effect of age at illness onset.

Findings: We found that early age at illness onset compared to later onset in the first diagnosed twin can be considered a major risk factor for developing schizophrenia in the second twin. Additionally, we found that the stronger genetic component in MZ twins compared to DZ twins is manifested in the proximity of assigned diagnosis within pairs.

Discussion: Early onset schizophrenia could be linked to a more severe genetic predisposition, indicating that age might be perceived as a clinical marker for genetic vulnerability for the illness.

Keywords: Age at onset; Nationwide register-based data; Schizophrenia; Twin study.

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Figures

Fig. 1
Fig. 1
Age at onset among all twins affected with schizophrenia (N = 448) and schizophrenia spectrum (N = 788) in twin pairs born 1951–2000 and identified by linkage of the Danish Twin Register and the Danish Psychiatric Central Research Register.
Fig. 2
Fig. 2
Time difference between onset of diagnosis in affected twin pairs with schizophrenia (a; N = 447 twin pairs) and schizophrenia spectrum (b; N = 787 twin pairs) respectively, based on information from linkage of the Danish Twin Register and the Danish Psychiatric Central Research Register in a national cohort of twin pairs born 1951–2000.
See this image and copyright information in PMC

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