Branched chain amino acids (BCAA) are essential elements of the human diet, which display increased plasma levels in obesity and regained particular interest as potential biomarkers for development of diabetes. To define determinants of insulin resistance (IR) we investigated 73 genes involved in BCAA metabolism or regulation by fine-scale haplotype mapping in two European populations with metabolic syndrome. French and Romanians (n = 465) were genotyped for SNPs (Affymetrix) and enriched by imputation (BEAGLE 4.1) at 1000 genome project density. Initial association hits detected by sliding window were refined (HAPLOVIEW 3.1 and PHASE 2.1) and correlated to homeostasis model assessment (HOMA_IR) index, in vivo insulin sensitivity (S_I) and BCAA plasma levels (ANOVA). Four genomic regions were associated with IR located downstream of MUT, AACS, SLC6A15 and PRKCA genes (P between 9.3 and 3.7 x 10⁻⁵). Inferred haplotypes up to 13 SNPs length were associated with IR (e.g. MUT gene with P < 4.9 x 10⁻⁵; Bonferroni 1.3 x 10⁻³) and synergistic to HOMA_IR. SNPs in the same regions were also associated with one order of magnitude lower P values (e.g. rs20167284 in the MUT gene with P < 1.27 x 10⁻⁴) and replicated in Mediterranean samples (n = 832). In French, influential haplotypes (OR > 2.0) were correlated with in vivo insulin sensitivity (1/S_I) except for SLC6A15 gene. Association of these genes with BCAA levels was variable, but influential haplotypes confirmed implication of MUT from BCAA metabolism as well as a role of regulatory genes (AACS and PRKCA) and suggested potential changes in transcriptional activity. These data drive attention towards new regulatory regions involved in IR in relation with BCAA and show the ability of haplotypes in phased DNA to detect signals complimentary to SNPs, which may be useful in designing genetic markers for clinical applications in ethnic populations.

Introduction. Osteoporosis (OP) affects 30% of postmenopausal women, often complicated by metabolic syndrome (MetS) with a still controversial role. We aimed to characterize MetS and its components in relation to bone mineral density (BMD), body mass index (BMI), and insulin resistance. Methods. Patients (n = 188) underwent DEXA scans, spine X-rays, and metabolic and hormonal investigations, including bone biomarkers, muscular strength, and physical performance tests, while insulin resistance was evaluated by the Homeostasis Model Assessment (HOMA-IR). Results. Patients with a normal BMD or osteopenia (n = 68) and with OP (n = 120) displayed 51.5% and 30.8% of MetS, but without differences in insulin resistance. When BMD was studied as a function of the cumulative MetS criteria and centiles of BMI, lower levels of BMD were observed beyond an inflection point of 27.2 kg/m² for BMI, allowing for further stratification as lean and overweight/obese (OW/OB) subjects. In contrast with lean individuals (n = 74), in OW/OB patients (n = 46), MetS was associated with HbA1c (p < 0.0037, OR 9.6, 95% CI [1.64–55.6]) and insulin resistance (p < 0.0076, OR 6.7, 95% CI [1.49–30.8]) in the context where BMD values were lower than those predicted from BMI in non-OP subjects. In OP patients with fragility fractures (31% of MetS), glycemia also appeared to be the dominant factor for MetS (p < 0.0005, OR 4.1, 95% CI [1.63–10.39]). Conclusions. These data indicate a detrimental effect of insulin resistance in MetS on OP patients, while the prevalence of the syndrome depends on the proportion of obesity. These findings provide new insights into the pathogenic role of MetS and reveal the need to consider different strata of BMI and insulin resistance when studying postmenopausal OP.

Branched-chained amino acids (BCAA) are essential dietary components for humans and can act as potential biomarkers for diabetes development. To efficiently estimate dietary intake, we developed a BCAA database for 1331 food items found in the French Centre d’Information sur la Qualité des Aliments (CIQUAL) food table by compiling BCAA content from international tables, published measurements, or by food similarity as well as by calculating 267 items from Greek, Turkish, Romanian, and Moroccan mixed dishes. The database embedded in MEDIPAD software capable of registering 24 h of dietary recalls (24HDR) with clinical and genetic data was evaluated based on archived 24HDR of the Saint Pierre Institute (France) from 2957 subjects, which indicated a BCAA content up to 4.2 g/100 g of food and differences among normal weight and obese subjects across BCAA quartiles. We also evaluated the database of 119 interviews of Romanians, Turkish and Albanians in Greece (27–65 years) during the MEDIGENE program, which indicated mean BCAA intake of 13.84 and 12.91 g/day in males and females, respectively, comparable to other studies. The MEDIPAD is user-friendly, multilingual, and secure software and with the BCAA database is suitable for conducting nutritional assessment in the Mediterranean area with particular facilities for food administration.

Introduction. The Fat Mass and Obesity-Associated (FTO) gene encodes a demethylase, which modulates RNA N6-methyladenosine (m6A) and plays a regulatory role in adipocyte differentiation and the pathogenesis of human obesity. Methods. To understand the potential role of FTO in osteoporosis (OP), we investigated five single nucleotide variations (SNVs) in intron 1 (rs8057044, rs8050136, rs9939609, rs62033406, and rs9930506) of the FTO gene, and a missense SNV i.e., rs3736228 (A1330V), located in exon 18 of the LRP5 gene, in a cohort of postmenopausal women (n = 188) from Central Europe. Genotyping was performed with an allele discrimination assay, while haplotypes were reconstructed in the population by PHASE 2.1. Results. The rs9930506 was strongly associated with OP (p < 0.0035), which was supported by Bonferroni correction (p < 0.0175), and all SNVs located in the FTO gene were more strongly associated with severe OP with fragility fractures. Among seventeen haplotypes detected for the FTO gene, two haplotypes (H1 and H9) were frequent (frequency > 10%) and distributed in three main haplotypes pairs (H1/H1, H1/H9 and H9/H9, respectively). The pathogenic pair H1/H9 was associated with a leaner phenotype, increased fracture risk, and a lower bone mineral density (BMD), and carried the heterozygous GA of rs9930506, while the protective pair H9/H9 was associated with an increased obesity risk and carried AA alleles of rs9939609. Conclusions. Concordant associations with OP, an increased fracture risk, and a lower BMD at all skeletal sites indicate that the FTO gene is a promising candidate for OP, explaining the complex relationship with obesity and offering new perspectives for the study of the epigenetic regulation of bone metabolism.

Introduction. The Fat Mass and Obesity-Associated (FTO) gene encodes a demethylase that modulates RNA N6-methyladenosine (m6A) playing a regulatory role in adipocyte differentiation and pathogenesis of human obesity. Methods. To understand the potential role of FTO in osteoporosis (OP) we investigated five single nucleotide variations (SNVs) in intron 1 (rs8057044, rs8050136, rs9939609, rs62033406, rs9930506) in a cohort of postmenopausal women (n = 188) from Central Europe. Genotyping was performed by allele discrimination assay while haplotypes were reconstructed in population by PHASE 2.1. Results. The rs9930506 was strongly associated with OP (P < 0.0035), supported by Bonferroni correction (P < 0.0175) and all SNVs were stronger associated with severe OP with fragility fractures. Among 17 haplotypes, two were frequent (h1 and h9) and distributed in three main haplotypes pairs (h1/h1, h1/h9, h9/h9). Pathogenic pair h1/h9 was associated with leaner phenotype, fractures and lower bone mineral density (BMD) and carried heterozygous GA of rs9930506, while protective pair h9/h9 was associated with obesity and carried AA alleles of rs9939609. Conclusions. Concordant associations with OP, fractures risk and lower BMD at all skeletal sites indicate FTO as a promising candidate for OP explaining complex relationship with obesity and offer new perspectives for the study of epigenetic regulation of bone metabolism.