Evaluation of anthropometry as an alternative to DXA as predictor of low bone mineral density in children and adolescents with cystic fibrosis.

BACKGROUND & AIMS: Low bone mineral density (BMD) for age in people with Cystic Fibrosis (CF) is associated with worse nutritional status. The aim of this study is to assess body composition by anthropometry as a predictor of BMD in people with CF. METHODS: Multicenter cross-sectional study with 39 people aged 5 and 20 years with CF. BMD was assessed by dual energy x-ray emission (DXA) in the incidence of the total body less head (TBLH) and the TBLH Z-score (Z-TBLH) was calculated, adjusted by sex, age, height and ethnicity. Anthropometry was assessed by weight, height, mid-upper arm circumference (MUAC) and triceps skinfold (TSF). Arm muscle area (AMA) and Body Mass Index (BMI) were calculated. Lean mass (LM), fat mass (FM) and free-fat mass (FFM) were identified by DXA. The molecular analysis method by sequencing was used to identify and classify the participants regarding the presence of the F508del pathogenic variant of the CFTR gene. Statistical models of simple and multiple linear regression were created to establish the predictive power of Z-TBLH in the variables. RESULTS: Average age of the participants was 13.31 ± 3.86 years, 59% of whom were male. They showed more LM (30.97 Kg ± 11.29) than females (23 Kg ± 6.73). 20 of 30 participants (66.7%) had at least copy of F508del. Among the multiple models, adjusted by height, age and sex, it found BMI (R2 = 0.367), Weight (R2 = 0.220), AMA (R2 = 0.338) as significant predictors of Z-TBLH. The final model composed of AMA, TSF and Age (p = 0.001; R2 = 0.381) had AMA and Age as significant predictors. AMA was associated with an increase in the BMD Z-score in the participants studied. 66.7% of genetically tested participants had the F508del pathogenic variant. The presence of the F508del variant was associated with worse nutritional status. CONCLUSION: A statistical model composed of the values of AMA, TSF and Age can predict Z-TBLH, as well as anthropometric variables Weight, or BMI, or AMA associated with height, age and sex, in children and adolescents aged 5-20 years old, of both sexes. Anthropometric markers, as they are easy and relatively inexpensive to obtain, it is a promising alternative to the use of DXA in predicting BMD in these people with CF.

Relationship between BsmI polymorphism and VDR gene methylation profile, gender, metabolic profile, oxidative stress, and inflammation in adolescents.

INTRODUCTION: Background: the biological activity of vitamin D depends on the activity of its receptor or VDR. On the other hand, the activity of this receptor is influenced by its state of methylation. The objective of this study was to verify if the BsmI polymorphism of the VDR gene influences its methylation profile in adolescents. Secondly, it was to verify if the status of some metabolic factors (oxidative stress, inflammation, lipid profile, and glycemia) in the serum, and gender-adjusted vitamin D levels are independent factors with an influence on the VDR methylation profile. Methods and results: the study included 198 adolescents of both sexes, aged 15-19 years, who underwent testing for VDR gene methylation polymorphisms, serum vitamin D levels, and metabolic, oxidative stress, and systemic inflammation markers. It was observed that the BB genotype was less methylated than the other groups (26.1 % versus 30.3 %, and 29.3 % for Bb and bb, respectively), although without statistical differences between them. The odds ratio indicated a protection of 13 % (partially methylated) for vitamin D status, while alpha glycols increased the risk ratio (of being partially methylated) by 3 %. MDA was protective at a 28 % chance of risk that adolescents with higher levels of lipid peroxidation would be hypomethylated. Conclusion: we conclude that the methylation profile of the VDR gene is not influenced by the different BsmI polymorphism genotypes, and that serum vitamin D and serum markers of oxidative stress and inflammation can modulate this profile.

INTRODUCCIÓN: Antecedentes: la actividad biológica de la vitamina D depende de la actividad de su receptor, el VDR. Por otro lado, la actividad de este receptor está influenciada por su estado de metilación. El objetivo de este estudio es verificar si el polimorfismo BsmI del gen VDR influye en el perfil de metilación del mismo en los adolescentes. En segundo lugar, verificar si los factores metabólicos (estrés oxidativo, inflamación, perfil lipídico y glucemia) del suero y la vitamina D ajustada por sexo actúan independientemente de los polimorfismos sobre el perfil de metilación del VDR. Métodos y resultados: el estudio incluyó a 198 adolescentes de ambos sexos, de 15 a 19 años de edad, que se sometieron a análisis de polimorfismos de metilación del gen VDR, niveles de vitamina D, marcadores metabólicos, estrés oxidativo e inflamación sistémica. Se observó que el genotipo BB estaba menos metilado que los otros grupos (26,1 % contra 30,3 % y 29,3 % para Bb y bb respectivamente), aunque sin diferencias estadísticas entre ellos. El odds ratio indicó una protección del 13 % (parcialmente metilado) para el estado de la vitamina D, mientras que los alfa glicoles aumentaron el índice de riesgo (de estar parcialmente metilado) en un 3 %. La MDA fue protectora con un 28 % de probabilidad de riesgo de que los adolescentes con niveles más altos de peroxidación lipídica fueran hipometilados. Conclusión: concluimos que el perfil de metilación del gen VDR no está influenciado por los diferentes genotipos del polimorfismo BsmI y que la vitamina D y los marcadores de estrés oxidativo e inflamación en el suero pueden modular este perfil.