Evidence for a susceptibility gene for restricting anorexia nervosa on chromosome

Eating disorders, such as anorexia nervosa, have been shown to have a significant genetic component. A recent genome wide linkage analysis of 196 affected relative pairs with anorexia nervosa and related eating disorders, including bulimia nervosa, gave only modest evidence for linkage. This may be due to multiple interacting genes of weak to moderate effect or sample heterogeneity. Reducing sample heterogeneity would increase power to detect linkage. In our current study we have carried out linkage analysis in a subset (n = 37) of families where at least two affected relative pairs had diagnoses of anorexia nervosa, restricting subtype. Restricting anorexia nervosa (RAN) is a defined subtype of anorexia nervosa characterized by severe limitation of food intake without the presence of binge eating or purging behavior. When we restricted the linkage analysis to this clinically more homogenous subgroup, the highest multipoint NPL score of 3.03 was observed on chromosome 1p. Genotyping additional markers in this region led to a peak multipoint NPL score of 3.45. The data are consistent with the presence of a susceptibility locus for the restricting type of anorexia nervosa on chromosome 1p.