The Genesis 12–19 (G1219) Study: A Twin and Sibling Study of Gene–Environment Interplay and Adolescent Development in the UK

Abstract

The Genesis 12-19 (G1219) Study is an ongoing longitudinal study of a sample of UK twin pairs, non-twin sibling pairs, and their parents. G1219 was initially designed to examine the role of gene-environment interplay in adolescent depression. However, since then data have continued to be collected from both parents and their offspring into young adulthood. This has allowed for longitudinal analyses of depression and has enabled researchers to investigate multiple phenotypes and to ask questions about intermediate mechanisms. The study has primarily focused on emotional development, particularly depression and anxiety, which have been assessed at multiple levels of analysis (symptoms, cognitions, and relevant environmental experiences). G1219 has also included assessment of a broader range of psychological phenotypes ranging from antisocial behaviors and substance use to sleep difficulties, in addition to multiple aspects of the environment. DNA has also been collected. The first wave of data collection began in the year 1999 and the fifth wave of data collection will be complete before the end of 2012. In this article, we describe the sample, data collection, and measures used. We also summarize some of the key findings to date.

Molecular and genetic basis of depression

“…With the intention of reducing genetic and environmental heterogeneity of the subjects under study for depression, studies on twins, specially the monozygotic ones residing in same or two different environmental conditions, or adoption studies, where the children are of different genetic makeup but residing in a given environment, may reveal the heritability of a given polymorphism and its interaction with the environmental components (McAdams et al 2012). In an appropriate study, Byrne et al (2013) assessed the role of epigenetic modifications (methylation) in CpG sites in 12 monozygotic twins discordant for major depressive disorder (MDD) and another 12 monozygotic twins concordant for no MDD.…”

A Longitudinal Twin and Sibling Study of Associations between Insomnia and Depression Symptoms in Young Adults

“…This is noteworthy given that the G1219 study as a whole initially comprised families including parents who are more educated and more likely to own their own homes than representative samples. 19 Heritability is a population statistic, meaning that our results may not apply to other cohorts. This needs to be considered when interpreting the results of this study.…”

“…19 At wave 4 (for ease of presentation referred to herein as Time 1), a total of 1,556 individuals participated in the G1219 study. At wave 5 (referred to as Time 2), a total of 862 individuals participated.…”

“…Given the importance of the research question and the limited research addressing this topic to date, the aim of this study was to assess a sample of young adult twins and siblings 19 over a 5-year period in order to examine both concurrently and longitudinally:…”

Longitudinal Stability of Genetic and Environmental Influences on the Association between Diurnal Preference and Sleep Quality in Young Adult Twins and Siblings

“…The current study assessed associations between diurnal preference and sleep quality concurrently and longitudinally in a sample of young adult twins and siblings from the G1219 study (for a description of this study see McAdams et al 2013). We examined (1) stability of diurnal preference and sleep quality over time; (2) associations between diurnal preference and sleep quality concurrently and longitudinally; (3) stability of genetic and environmental influences on diurnal preference and sleep quality, within-phenotypes, over time; and (4) the extent of genetic and environmental overlap between phenotypes concurrently and longitudinally.…”