Is this the dawn of the groupOME?

Can the genome of the people around us really have a direct influence on our own health? Amelie Baud of the EMBL-EBI thinks so. We caught up with her to discuss mice, missing heritability and the potential of the full genetic ecosystem… 

Published in PLOS Genetics, a new study suggests the genetic makeup of life partners can impact health, anxiety and even healing in mice. Amelie Baud, Postdoctoral Fellow at the European Bioinformatics Institute (EMBL-EBI) sat down to discuss how, for the first time, this research identified an additional factor that contributes to health: the genetic makeup of an individual’s social partners.

“People influence your behaviour, health and wellbeing, and you influence theirs – this much we know already. What’s been missing is recognition that there is a genetic basis for this,” explains Amelie Baud of EMBL-EBI, who led the study. “If you’re a researcher looking for links between genotypes and disease, it is very important to take into consideration not only your patient but also their social environment.”

According to Baud’s new study, some of our traits may be affected by both our own genes and those of our social partners

Most traits are genetically controlled to some extent. This goes beyond physical traits such as dimples, freckles or a particular disease. According to Baud’s new study, some of our traits may be affected by both our own genes and those of our social partners. Research on social genetic effects (SGE) can uncover the biological mechanisms that determine how individuals influence one another. Such influence goes beyond mood, anxiety and depression. Unexpectedly, the researchers also found significant effects on traits such as immunity, weight and wound healing. The extent to which SGEs explain variation in biomedical traits is largely unknown. Building on existing research, Baud and her colleagues found that SGEs can explain up to 30% of the variation observed in certain traits, including wound healing and body weight.

In fact, for a number of traits, they found the effect of a partner’s genes is stronger than that of the individual’s own genes. This highlights just how important it is to consider the genes of our social partners. It would be unrealistic to measure all of the possible ways your social partners’ traits could influence your health. But measuring a partner’s genotype is straightforward, inexpensive and potentially revealing.

Heritability is the contribution of direct genetic effects to a specific trait, such as a disease. According to Baud, current estimates of heritability could be biased by SGEs. So much so in fact, SGEs may be a piece of the ‘missing heritability’ puzzle in studies of complex traits in human populations. The missing heritability problem arises from two different approaches to calculating the association between traits and small differences in DNA sequences (genotype-to-phenotype associations). The first aims to quantify the overall contribution of direct genetic effects to a trait, without identifying specific genes. Instead, researchers compare the levels of genetic similarity and trait similarity between pairs of individuals.

Research into social genetic effects can help researchers better calculate the influence of a patient’s own genotypes on their disease progression

The second approach, genome-wide association studies (GWAS), aims to identify specific places in the genome where DNA differences give rise to different traits. But there is a gap between the calculated heritability of a trait and the cumulative effect of GWAS loci. This gap is called ‘missing heritability’. Research into social genetic effects can help researchers better calculate the influence of a patient’s own genotypes on their disease progression. This would make it easier for patients and doctors to identify the best way to intervene when the patient’s health is affected by their partner.

In this study, the researchers used two strains of mice, grey and black, and set them up as unrelated ‘roommates’ in different combinations. They studied social genetic effects by measuring associations between traits such as wound healing, body weight, anxiety and depressed mood in individual mice and the genetic makeup (strain) of their cage mates. “You can detect social genetic effects even if you don’t know the specific traits that mediate how an individual is influenced by their social environment,” says Baud. “We only measured traits like healing, anxiety and body weight in mice and genotypes in their cage mates. We found a surprisingly high contribution of the strain of the cage mates to the variation in these measures.”

[caption id="attachment_59072" align="alignnone" width="620"] This research suggests the exert of others' influence on a person's wellbeing.[/caption]

The researchers also re-analysed an existing dataset from 2500 genetically unique mice to investigate more health-related traits, studying a population that is genetically more similar to the human population. They found that social genetic effects explained up to 29% of variance in the traits measured, including wound healing, anxiety, immune function, and body weight. The strong influence of the partner’s genes suggests that Baud and her colleagues are on the right track. “Although this study was carried out in mice living together, it provides food for thought about how individuals can be influenced by the genetic makeup of the people in their lives – and vice versa,” says Dr Oliver Stegle of EMBL-EBI, an author on the study. “The methods and approaches we developed could certainly be applied to human studies.”

For example, an individual’s sleep preferences have a genetic component. So if your partner is a night owl and keeps you awake past your bedtime, their genotypes might be partly to blame. “Imagine you are an early bird and your partner is a night owl. Your partner’s sleeping pattern might affect your own and you could soon end up going to sleep later than you’d like,” explains Baud.

However, if research showed there was indeed a connection between your illness and the genes that control your partner’s sleeping pattern, then your doctor could better probe your life habits and give useful advice

“Now, say you develop an illness, but don’t mention the sleep situation to your doctor because you don’t realise that it’s important. This could cause problems with diagnosis or treatment. However, if research showed there was indeed a connection between your illness and the genes that control your partner’s sleeping pattern, then your doctor could better probe your life habits and give useful advice. You and your night owl could then make the right change to ensure you get the sleep you need to heal. With this change, you would be mitigating the negative influence of the night owl’s genotypes on your health.”

By studying social genetic effects, the researchers hope to learn more about the mechanisms whereby people influence one another. “As a geneticist I want to provide doctors with information to understand the mechanisms and causal pathways behind a disease, so they have a better idea of how to intervene to help their patient heal,” says Baud. “Our goal is to include the full genetic ecosystem to understand how we influence one another.”

[caption id="attachment_59232" align="alignnone" width="650"] Click here for a short video of Amelie Baud and her team's work.[/caption]

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Dr Amelie Baud is a Sir Henry Wellcome fellow in the Stegle research group at the European Bioinformatics Institute (EBI) in Hinxton, Cambridge, part of the European Molecular Biology Laboratory

Published article: Baud A., et al. (2017) Genetic variation in the social environment contributes to health and disease. PLOS Genetics (in press). Published online 26 January. DOI: 10.1371/journal.pgen.1006498

Data available in ArrayExpress: www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-5276