Dr. Cyntha Bulik: Q&A About Anorexia Nervosa Genetics Study


A genome-wide association study or GWAS for short is basically a study in which you get a large sample of
individuals that have a particular disorder or trait and a large sample of
people who don’t have that trait and what it allows us to do is we genotype
those people and we sort of slather about a million markers across the
entire genome and then we compare the genomes of people with the illness to
people without the illness and where significant differences arise is where
genes that influence risk for that disorder might lie. In its most basic
sense this study confirms that there’s a genetic component to anorexia nervosa
but it takes us one step further than that what it’s done is it’s identified
eight areas on the genome where genes that influence risk for anorexia nervosa
may lie now although this is a breakthrough it’s also just a beginning
because we’re anticipating that there are going to be hundreds of genes
associated with anorexia nervosa so that’s the first finding the second
finding is really intriguing and this is actually what we call genetic
correlations so we took all of the information underlying this GWAS for
anorexia nervosa and we correlated it with 447 other GWAS’s of other traits
from other psychiatric disorders to metabolic phenotypes to educational
attainment and a number of significant finding significant correlations arose
and the pattern of correlations is such that there is very clear positive
genetic correlations between anorexia nervosa and other psychiatric disorders
like obsessive-compulsive disorder depression and anxiety disorders and in
fact that genetic correlation with obsessive-compulsive disorder
is one of the strongest positive genetic correlations in psychiatric genetics and
the neat thing about that is it mirrors what we see in the clinic so often we
see people with anorexia who have OCD depression and anxiety but basically the
genes are now telling us that what we’re seeing is
due to genetic factors which is a really interesting outcome but we take it one
step further so in addition other types of genetic correlations that we saw are
with a bunch of metabolic and anthropometric or body measurement
phenotypes so suddenly we see that anorexia nervosa is not only a
psychiatric disorder but it also has a metabolic component and this is a novel
finding from this study so traditionally anorexia nervosa has
been viewed primarily through a psychological lens and now I think what
we need to do is we need to add a second lens and we need to start looking
through that metabolic lens as well this doesn’t immediately tell us what the
underlying biology is but it points toward clear next steps of research that
need to be done we need to understand exactly what the metabolic component is
and how it influences anorexia in the interim one very important message is
how critical it is to adequately renourish people with anorexia nervosa
especially in the United States we often see that insurance companies will do
eyes treatment prematurely so people will be discharged from the hospital
before their bodies have had an opportunity to sort of react will abate
or stabilize at a healthy weight and so this suggests that getting the
metabolism stabilized again might be a very important in fact core component to
recovery from anorexia nervosa. One of the main principles behind GWAS is to
elucidate biology what’s the underlying biology of the illness in this case
anorexia nervosa and we’ve identified these first eight genes and we have some
hints about how they’re starting to a sword in pathways but as we increase our
sample size and identify more genes those pathways are going to become more
clear and then what we’re hoping to do is engage our physiologist friends our
neuroscientist friends our pharmacogenetic friends and start
actually developing medications that directly target the
underlying biology of the illness because right now we have no medications
that are effective in the treatment of anorexia nervosa. so I think there are
three limitations of this study and even though people here 17,000 people with
anorexia it makes them think that it’s a big study it’s actually just a
moderately sized GWAS so we’re actually aiming to get a hundred
thousand participants so sample size is one of the limitations a second
limitations is we don’t have enough men and we really want to understand whether
the same genes that influence risk for anorexia and girls and in women also
influence risk for anorexia and men so as we expand our sample size we’re gonna
have to work really hard to recruit men to participate and then the third thing
is this study was primarily on people of European ancestry because when we
started the study we actually didn’t have the techniques to analyze more
diverse samples but now we have those techniques so as we increase our sample
size we’re going to sample widely and we’re going to make sure we have
representation from all racial and ethnic categories. A really important
thing for people to keep in mind when they interpret the results of this study
is that genetics are not destiny so when we’re born we get 50% of our genes from
our mother and 50% of our genes from our father in that mix of genes you’re gonna
have a certain number of risk genes for anorexia nervosa but you’re also can
have some buffering genes or genes that make it less likely for you to develop
that illness and then plus we have to throw in the environment so in the
environment you have high risk environmental situations that you also
have buffering environmental situations and it’s those four buckets the risk
genes buffering genes risk environment and buffering environment that together
make up your risk so it’s very complicated how at risk you are and
who’s at risk for developing this illness. The next study we’re going to expand beyond anorexia nervosa we’re going to
continue collecting individuals who had anorexia nervosa but we’re also going to
broaden out to the other eating disorders so we’re going to be
recruiting people to participate who have bulimia nervosa and binge eating
disorder and this study is called edgy or the eating disorders genetics
initiative and it’s going to be easier to participate in this one because for
ANGI we had to collect blood from everyone but technology has advanced in
the last six years and now all we have to do is spit into a tube and fill out
some questionnaires online so stay tuned we’ll be launching EDGI soon and our
goal is to get a hundred thousand participants people who have had eating
disorders at any time in their life. Even though this is a starting point it
is not too early for us to engage people from other fields it would be wonderful
to have people who really study metabolism for their life for their
career to start looking at these data and see where we can go with it it’s not
too early to get people involved from Pharma who are interested in drug
discovery because one of the things that we know especially from all of these
genetic correlations is genetic information about anorexia doesn’t just
tell us about anorexia it tells us about all of these other psychiatric disorders
that it’s related to and now we know it tells us about all sorts of metabolic
traits as well so there are far-reaching implications now that we can start
delving deeper in on a biological level

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