ESPE Yearbook of Paediatric Endocrinology

In Brief: The authors analysed data from the nationwide Child and Adolescent Twin Study in Sweden (CATSS) to estimate the heritability of avoidant restrictive food intake disorder (ARFID) as defined by DSM-5 criteria. Of the 16 951 twin pairs born between 1992 and 2010, 682 (2.0%) children were identified to have ARFID. By modelling shared risk in monozygous compared to dizygous twin pairs, they estimated the heritability of ARFID as 79% (95%CI, 70–85).

Comment: While ARFID is not known to have an endocrine aetiology, we may see these patients in our clinics due to its impact on poor growth and delayed pubertal maturation. It is a cause of significant individual, family, and social impairment and can be life threatening.

ARFID is distinguishable from anorexia nervosa by its earlier age at onset, even from infancy, and by the lack of motivation by body image concerns or drive for thinness. Instead, it may be characterised by a lack of interest in food, fear of choking, vomiting or allergic reaction, or linked to autistic traits such as sensory sensitivity to food texture, smell, or taste. It is even thought to be on the rise in adults, linked to the popularity of severe restriction or food avoidance diets.

The headline finding of this paper is striking. A condition that was thought to be triggered by a wide range of stochastic factors, from acute allergies to distressing early experiences of eating, is now shown to be highly heritable – indeed, extremely heritable. There are few complex diseases or traits that have such a high heritability estimate, 79% is around the same heritability as adult height. The authors comment that this estimate is similar or higher than for other mental health traits: autism 64–91%; schizophrenia 79%; ADHD: 77–88%; bipolar disorder: 50–71%. By contrast, heritability estimates for other eating disorders are lower: anorexia nervosa 48–74%; bulimia nervosa 55–61%; binge-eating disorder 39–45%.

Now that ARFID can be considered a highly genetic condition, the next step is to explore the underlying genetic factors, molecular mechanisms and biological pathways that contribute to its pathogenesis. Hopefully this will reveal effective preventive and therapeutic interventions.