Summary:
Objective: Anorexia nervosa is a serious eating disorder of unknown etiology
that occurs mainly in adolescent girls and young women. This condition is
associated with decreased bone mineral density and greater lifetime risk for
fractures.Because approximately 45% of the bone mineral content is acquired
during puberty, occurrence of anorexia nervosa at this time may prevent the
attainment of optimal bone mass.Study design: Prospective case-control study
Methods: Girls diagnosed with AN according to the criteria of APA (proposed
DSM-V, 2012) took part in this study. We used pyrosequencing to analyze single
nucleotide polymorphisms of genes encoding vitamin D receptor (VDR), estrogen
receptor alpha (Esr1), collagen type I (COL1A1), and calcitonin receptor (CTR).
Relationships between genotype and body mass index (BMI), cycling status,
circulating concentrations of estradiol (E2), and lumbar spine bone mineral
density (LBMD and LBMD Z-scores) were determined in 40 girls with anorexia
nervosa and 10 age-matched controls.
Results: We found that cases had lower LBMD Z-scores and serum E2
concentrations and were more likely to have amenorrhea. Among cases, amenorrhea
was associated with low serum E2 level. The distribution of CTR-AluI genotypes
differed between groups, but this polymorphism was not associated with LBMD
Z-score. Distribution of Esr1-XbaI genotypes did not differ between groups, but
the AA genotype was associated with decreased LBMD Z-score (-1). Carriers of
the A allele were more likely to have decreased LBMD Z-score regardless of E2
serum concentrations. Carriers of the G allele were more likely to have a
reduced risk of decreased LBMD Z-score which depends on the levels of
circulating estradiol.
Conclusions: In our study, although patients with anorexia nervosa were more
likely to have the wild type (TT) calcitonin receptor polymorphism than
age-matched controls, CTR-AluI genotype was not associated with LBMD Z-score.
Anorexic patients with wild type genotype Esr1-XbaI receptor are in greater
risk of decreased BMD in relation to those with the mutated gene, since it
appears that there is an acting model further increasing the risk through
allele action. Prompt recognition of these patients may contribute to the
prevention of adverse sequelae on bone metabolism through early administration
of the proper therapeutic treatment.
Keywords:
Adolescence, Anorexia Nervosa, Bone Metabolism, Bone Mineral Density, Single-Nucleotide Polymorphisms
