Genetic perspective of eating disorders is on the rise among adolescents and their families. It was that children of families who are prone to such disorders were a small fraction of the total population, but now the ratio has risen to almost one in every two. This sudden surge in the prevalence of these disorders is due to complex factors like gene-environment interaction, heredity, and social and lifestyle patterns. While binge disorders like bulimia nervosa, anorexia nervosa, and obesity are associated with several genes, the environmental circumstances that support it are also innumerable.
In an ongoing study published in the peer-reviewed Journal of Neuroscience, geneticists studied nearly 2,000 twins whose parents had been diagnosed with one or more eating disorder over a 35-year period. The researchers found that the disorder prevalence rose sharply with age. Of those with the disorder, those in their thirties had the highest rate of familial aggregation, which means that both members of a family had the disorder.
Because of the increasing number of people with the disorder, there are more research studies to be done. One of these is the Genome Wide Association Study (GGAS), a project funded by the National Institutes of Health. This study found two common genetic factors that contribute to the onset of an eating disorder. These are higher heritability and lower heritability with age. Specifically, higher heritability indicates that genetic differences account for the differences in the risk for obesity. It is unknown why lower heritability tends to occur with age but not obesity.
Another study from Autism Genome sequencing by Autism Genetic Research Institute found evidence that monozygotic (identical) twins share a greater proportion of their disease risk than dizygotic (identical) twins. Also, identical twins tend to share a greater physiological component of autism. These findings are important in understanding familial aggregation of disorders as they may also explain why some families have higher rates of autism than other families. It is important to note that autism spectrum disorders remain highly heritable even when a third parent carries the disorder.
Genetic perspective of eating disorders was further analyzed in another study from Autism Genetic Research Institute that found strong heritability of PDD-NOS versus non PDD-NOS twins. Specifically, they examined four pairs of female monozygotic twins and found that in each pair, there was a significant difference in PDD-NOS disorder trait scores. Specifically, they found that in the monozygotic twins, there was a significantly greater variance in trait neuroticism, social networking anxiety, and perceived control, all of which are associated with adult attention and behavior management problems.
