Eating disorder portion of the vulnerability to develop eating disorders can be inherited, and there is evidence to show that there is a genetic locus that shows susceptibility for developing anorexia nervosa. About 60% of eating disorder cases are attributable to biological and genetic components. Other cases are due to external reasons or developmental problems. There are also other neurobiological factors at play tied to emotional reactivity and impulsivity that could lead to binging and purging behaviors. Epigenetics: Epigenetic mechanisms are means by which environmental effects alter gene expression via methods such as DNA methylation; these are independent of and do not
Other specified feeding or eating disorder in the literature, as it was perceived to be uncommon compared to the other defined eating disorders. In "DSM-III-R", published in 1987, the Atypical Eating Disorder category became known as Eating Disorder Not Otherwise Specified (EDNOS). "DSM-III-R" included examples of individuals who would meet criteria for EDNOS, in part to acknowledge the increasingly recognized heterogeneity of individuals within the diagnostic category. In 1994, "DSM-IV" was published and expanded EDNOS to include six clinical presentations. These presentations included individuals who: A disadvantage of "DSM-IV"'s broad EDNOS category was that people with very different symptoms were still classified as having the same