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The eating disorders anorexia nervosa and bulimia nervosa traditionally have been viewed as sociocultural in origin. However, recent behavioral genetic findings suggest substantial genetic influence on these disorders. Molecular genetic research of these disorders is in its infancy, but initial results are promising. This article reviews findings from family, twin, and molecular genetic studies that support substantial genetic influences on disordered eating and highlights additional areas for future research. Introduction Anorexia nervosa (AN) and bulimia nervosa (BN) are disorders characterized by abnormal patterns of eating behavior and disturbances in attitudes and perceptions toward weight and shape.

In AN, there is an extreme fear of weight gain despite increasing emaciation. BN usually emerges after a period of dieting, and is characterized by alternating patterns of binge eating and compensatory behavior. Binge eating, which is the consumption of a large amount of food in an uncontrollable manner, is typically followed by either self-induced vomiting, excessive exercise, fasting, and/or the misuse of laxatives, diuretics, or enemas. Although abnormally low body weight excludes a BN diagnosis, 25 to 30 percent of patients with BN have a prior history of AN. – Common to individuals with AN and BN are pathological concern with weight and shape, depression, and anxiety.

– The etiology of these disorders is presumed to be influenced by developmental, social, and biological processes., However, the exact nature of these interactive processes remains incompletely understood. Cultural attitudes toward thinness have relevance to the psychopathology of eating disorders, but they are unlikely to be sufficient to account for the pathogenesis of these disorders. Notably, dieting behavior is quite common in industrialized countries throughout the world, yet AN and BN affect only an estimated 0.3 to 0.7 percent, and 1.7 to 2.5 percent, respectively, of females in the general population.

Moreover, numerous descriptions of AN date from the middle of the 19th century suggesting that factors other than modern culture play an etiologic role. In addition, both syndromes have a relatively homogeneous clinical presentation, sex distribution, and age-of-onset, supporting the possibility of some biological susceptibility. This is not to discount the role of culture, as the introduction of Western ideals of thinness may serve to release a biological propensity toward eating disorders possibly by increasing behaviors, such as dieting, that may trigger the spiral of disordered eating. Recent findings from behavior genetic studies suggest that this biological vulnerability might be genetic in nature.

In this article, I will highlight these emerging findings and suggest areas for future research. Heritability Family studies. Family studies provide initial data regarding genetic influence on a disorder by establishing whether it clusters amongst biologically related individuals. Controlled family studies have generally found increased rates of eating disorders in relatives of women with AN and BN compared to relatives of controls. – Findings from the largest and most systematic studies, suggest a 7 to 12-fold increase in the prevalence of AN and BN in relatives of eating disordered probands.

This clustering of eating disorders in families of AN and BN individuals provides strong support for familial transmission of both disorders. However, given that first-degree relatives share both genes and environments, these studies cannot differentiate genetic versus environmental causes for the observed familiality. Systematic studies of twins are the means by which to disentangle the relative etiological influence of genes and environment. Twin studies.

Twin studies differentiate genetic from environmental effects by comparing similarity for a trait/disorder between identical (monozygotic [MZ]) and fraternal twins (dizygotic [DZ]). This comparison is based on the fact that MZ twins share all of their genes identical by descent, whereas DZ twins share, on average, half of their genes identical by descent. Consequently, MZ twin correlations that are approximately two times greater than DZ twin correlations suggest genetic effects. My disney kitchen download free for pc. In general, greater MZ relative to DZ twin similarity for AN and BN has generally been found.