Genome-wide DNA methylation profiling in anorexia nervosa discordant identical twins.

Up until now, no study has looked specifically at epigenomic landscapes throughout twin samples, discordant for Anorexia nervosa (AN). Our goal was to find evidence to confirm the hypothesis that epigenetic variations play a key role in the aetiology of AN. In this study, we quantified genome-wide patterns of DNA methylation using the Infinium Human DNA Methylation EPIC BeadChip array ("850 K") in DNA samples isolated from whole blood collected from a group of 7 monozygotic twin pairs discordant for AN. Results were then validated performing a genome-wide DNA methylation profiling using DNA extracted from whole blood of a group of non-family-related AN patients and a group of healthy controls. Our first analysis using the twin sample revealed 9 CpGs associated to a gene. The validation analysis showed two statistically significant CpGs with the rank regression method related to two genes associated to metabolic traits, PPP2R2C and CHST1. When doing beta regression, 6 of them showed statistically significant differences, including 3 CpGs associated to genes JAM3, UBAP2L and SYNJ2. Finally, the overall pattern of results shows genetic links to phenotypes which the literature has constantly related to AN, including metabolic and psychological traits. The genes PPP2R2C and CHST1 have both been linked to the metabolic traits type 2 diabetes through GWAS studies. The genes UBAP2L and SYNJ2 have been related to other psychiatric comorbidity.

Impaired executive functioning influences verbal memory in anorexia nervosa.

BACKGROUND: How executive functioning affects delayed verbal recall in AN has never been tested. We investigated the influence of speed of information processing (SIP) and inhibition on delayed verbal recall in females with AN. METHODS: Measures of SIP and inhibition from 35 females with AN were analyzed using hierarchical multiple regression after controlling for age, depressive symptomatology and body mass index. Each predictor was evaluated using structure coefficients, common variance and dominance weights. RESULTS: The combination of measures of SIP and inhibition accounted for almost 80% of the variance on the delayed recall of the story recall task. When the rest of the variables were partialled out, SIP and inhibition accounted for more than 50% of the variance. CONCLUSIONS: As it occurs with visuospatial abilities in AN, basic cognitive abilities such as speed of information processing and cognitive inhibition may affect other cognitive functions such as delayed verbal memory regardless of immediate recall. These findings may help interpret performance on cognitive tests in future research.