High intake of sugar remains an important nutritional problem in children of many European countries. Interventions aiming to prevent this diet pattern may optimize their impact by targeting dietary habits on Fridays and weekends. Furthermore, when conducting dietary assessment in children, data from weekends and Fridays in combination with a selection of Mondays to Thursdays are needed to capture habitual sugar intake. Age and dietary cultures should also be considered in dietary intervention and assessment as effect modifications were seen for both age and country.

Objective: To evaluate two saliva collection methods for DNA yield and quality as applied to a large, integrated, multi-centre, European project involving the collection of biological material from children. Design: Cross-sectional multi-centre comparative study in young children. Methods: Saliva samples were collected from 14,019 children aged 2-9 years from eight European countries participating in the IDEFICS (Identification and prevention of Dietary-and lifestyle-induced health EFfects In Children and infantS) study. This involved either the collection of 2 ml of saliva from children who were able to spit, or using a sponge to collect whole saliva and buccal mucosal cells from the inside of the mouth of younger children unable to spit. Samples were assembled centrally in each participating centre and subsequently dispatched for DNA extraction and biobanking to the University of Glasgow. A subgroup of 4,678samples (approximately 33% of sampled individuals) was chosen for DNA extraction prior to genotyping. Results: The whole saliva collection method resulted in higher DNA yield than the sponge collection method (mean ± SD; Saliva: 20.95 ± 2.35 µg,; Sponge: 9.13 ± 2.25 µg; P<0.001). DNA quality as measured by A 260 /A 280 was similar for the two collection methods. A minimum genotype calling success rate of 95% showed that both methods provide good quality DNA for genotyping using TaqMan® allelic discrimination assays. Conclusions: Our results showed higher DNA yield from the whole saliva collection method compared to the assisted sponge collection. However, both collection methods provided DNA of sufficient quantity and quality for large-scale genetic epidemiological studies.

ObjectivesWe investigated cross-sectionally and longitudinally the relationship between FTO rs9939609 and obesity-related characteristics in the European children of the IDEFICS project and the interaction of this variant with a lifestyle intervention.Population and MethodsA cohort of 16224 children (2–9 years) was recruited into a population-based survey (T0) from eight European countries. A second survey (T1) reassessed the children two years later. A random sample of 4405 children was extracted for genetic studies. 3168 children were re-examined two years later. Half of them underwent a lifestyle intervention program. The FTO rs9939609 was genotyped. Weight, height, waist circumference, triceps and subscapular skinfolds were measured at T0 and T1.ResultsAt T0, the risk A allele of rs9939609 was significantly associated with higher values of body mass index (BMI), waist circumference and skinfolds (age, sex, and country-adjusted p-values: all p<0.001) and with a statistically significant increased risk of overweight/obesity.Over the two year follow-up, no interaction between genotype and intervention was observed. The A allele was associated to a significantly higher increase in all the anthropometric variables examined at T0 independently from the study group (intervention versus control) (p-values: all p<0.002, adjusted for age, sex, country, intervention/control study group, T0 values, and individual time interval between T0 and T1). Over the two-year follow–up, 210 new cases of overweight/obesity occurred. A statistically significant higher incidence of overweight/obesity was associated to the A allele [ORA = 1.95, 95% CI = (1.29; 2.97)].ConclusionsWe confirmed the association between the FTO rs9939609 and body mass and overweight/obesity risk in European children. The main finding of the study is that the A allele carriers present higher increase of body mass and central adiposity over time and higher risk of developing overweight/obesity during growth, independently from intervention measures.

Neuromedin U, encoded by the NMU gene, is a hypothalamic neuropeptide that regulates both energy metabolism and bone mass. The beta-2 adrenergic receptor, encoded by the ADRB2 gene, mediates several effects of catecholamine hormones and neurotransmitters in bone. We investigated whether NMU single nucleotide polymorphisms (SNPs) and haplotypes, as well as functional ADRB2 SNPs, are associated with bone stiffness in children from the IDEFICS cohort, also evaluating whether NMU and ADRB2 interact to affect this trait. A sample of 2,274 subjects (52.5% boys, age 6.2±1.8 years) from eight European countries, having data on calcaneus bone stiffness index (SI, mean of both feet) and genotyping (NMU gene: rs6827359, rs12500837, rs9999653; ADRB2 gene: rs1042713, rs1042714), was studied. After false discovery rate adjustment, SI was significantly associated with all NMU SNPs. rs6827359 CC homozygotes showed the strongest association (recessive model, Δ = −1.8, p = 0.006). Among the five retrieved haplotypes with frequencies higher than 1% (range 2.0–43.9%), the CCT haplotype (frequency = 39.7%) was associated with lower SI values (dominant model, Δ = −1.0, p = 0.04) as compared to the most prevalent haplotype. A non-significant decrease in SI was observed in in ADRB2 rs1042713 GG homozygotes, while subjects carrying SI-lowering genotypes at both SNPs (frequency = 8.4%) showed much lower SI than non-carriers (Δ = −3.9, p<0.0001; p for interaction = 0.025). The association was more evident in preschool girls, in whom SI showed a curvilinear trend across ages. In subgroup analyses, rs9999653 CC NMU or both GG ADRB2 genotypes were associated with either lower serum calcium or β-CrossLaps levels (p = 0.01). This study in European children shows, for the first time in humans, a role for NMU gene through interaction with ADRB2 gene in bone strength regulation, more evident in preschool girls.

on behalf of the IDEFICS Consortium OBJECTIVE: We investigated the relationship between matrix metalloproteinase 3 (MMP3) polymorphisms and adiposity indices in European children of the IDEFICS (Identification and Prevention of Dietary-and Lifestyle-Induced Health Effects in Children and Infants) project. SUBJECTS: A total of 16 224 Caucasian children (2-9 years) were recruited into a population-based survey from eight European countries. In all, 4540 children were randomly selected for genetic studies (T0); 3238 children were re-examined 2 years later (T1). Anthropometric measures were collected by standardized protocols at T0 and T1. RESULTS: Six variants of MMP3 gene were genotyped. Homozygotes for the variant A allele of rs646910 and for the H3 haplotype had higher hip circumference (P ¼ 0.002 and 0.001; age, sex and country adjusted) at T0. The association remained significant after false discovery rate (FDR) correction. At T1, subjects carrying rs646910 A/A genotype or H3/H3 diplotype showed significantly higher values of body mass index, waist and hip circumference and sum of tricipital and subscapular skinfolds, all associations remaining significant after FDR correction (P ¼ 0.020-0.048). CONCLUSIONS: We showed for the first time an association between the MMP3 rs646910 variant and indices of adiposity in European children, highlighting the involvement of metalloproteinase genes in adipose tissue remodeling and growth.