Effects of vitamin D and estrogen receptor polymorphisms on bone mineral density in adolescents with anorexia nervosa

Background: Anorexia nervosa (AN) is a serious eating disorder that is associated with decreased bone mineral density (BMD) and greater lifetime risk for fractures. The aim of this study was to determine the correlation between BMD and genetic polymorphisms in AN. Methods: This case-control study analyzed vitamin D receptor (VDR) (VDRBsml, VDRFokl) and estrogen receptor (ESR) (ESR1Xbal, ESR1Pvull) polymorphisms in 45 adolescents diagnosed with AN and 46 age-matched healthy controls. BMD values of the AN group were classified as low or normal, and polymorphisms were compared between cases and controls. The effects of body mass index (BMI), duration of disease and amenorrhea on BMD were also evaluated. Results: In girls with AN, a positive effect of the bb genotype of VDRBsmI polymorphism on femur Z-scores (p = 0.103) and of the Ff genotype of VDRFokI polymorphism on vertebra Z-scores (p = 0.097) was observed. In boys with AN, a positive effect of the Ff genotype of VDRFokI polymorphism on vertebra BMD (g/cm(2)) was detected (p = 0.061). No association was detected between ESR polymorphisms. An inverse relationship was observed between BMD and duration of illness and amenorrhea. A direct relationship was detected between BMD and BMI. Conclusions: Specific VDR gene polymorphism genotypes may have positive effects on BMD in patients with AN. Additionally, the lack of association between ESR gene polymorphisms on BMD could be attributed to the low estrogen status of the patient.