Increase in adiposity from childhood to adulthood predicts a metabolically obese phenotype in normal-weight adults.

Normal weight is associated with a favorable cardiometabolic risk profile and low risk of type 2 diabetes and cardiovascular disease. However, some normal-weight individuals-the "metabolically obese normal weight" (MONW)-show a cardiometabolic risk profile similar to the obese. Previous studies have shown that older age, central body fat distribution, and unfavorable lifestyle increase the risk of MONW. However, the role of early-life factors in MONW remains unknown. We examined the associations of early-life factors with adult MONW in 1178 individuals from the Cardiovascular Risk in Young Finns study who were followed up from childhood to adulthood. The strongest early predictor for adult MONW was an increase in BMI from childhood to adulthood (p = 3.1 × 10-11); each 1 SD increase in BMI z-score from childhood to adulthood led to a 2.56-fold increase in the risk of adult MONW (CI 95% = 1.94-3.38). Other significant predictors of adult MONW were male sex (OR = 2.38, 95% = 1.63-3.47, p = 7.0 × 10-6), higher childhood LDL cholesterol (OR = 1.41 per 1 SD increase in LDL cholesterol, CI 95% = 1.14-1.73, p = 0.001), and lower HDL cholesterol (OR = 1.51 per 1 SD decrease in HDL cholesterol, CI 95% = 1.23-1.85, p = 5.4 × 10-5). Our results suggest that an increase in adiposity from childhood to adulthood is detrimental to cardiometabolic health, even among individuals remaining normal weight.

Education as a moderator of genetic risk for higher body mass index: prospective cohort study from childhood to adulthood.

OBJECTIVES: The life-course development of body mass index (BMI) may be driven by interactions between genes and obesity-inducing social environments. We examined whether lower parental or own education accentuates the genetic risk for higher BMI over the life course, and whether diet and physical activity account for the educational differences in genetic associations with BMI. SUBJECTS/METHODS: The study comprised 2441 participants (1319 women, 3-18 years at baseline) from the prospective, population-based Cardiovascular Risk in Young Finns Study. BMI (kg/m2) trajectories were calculated from 18 to 49 years, using data from six time points spanning 31 years. A polygenic risk score for BMI was calculated as a weighted sum of risk alleles in 97 single-nucleotide polymorphisms. Education was assessed via self-reports, measured prospectively from participants in adulthood and from parents when participants were children. Diet and physical activity were self-reported in adulthood. RESULTS: Mean BMI increased from 22.6 to 26.6 kg/m2 during the follow-up. In growth curve analyses, the genetic risk score was associated with faster BMI increase over time (b=0.02, (95% CI, 0.01-0.02, P<0.001)). The association between the genetic risk score and BMI was more pronounced among those with lower educational level in adulthood (b=-0.12 (95% CI, -0.23-0.01); P=0.036)). No interaction effect was observed between the genetic risk score and parental education (b=0.05 (95% CI, -0.09-0.18; P=0.51)). Diet and physical activity explained little of the interaction effect between the genetic risk score and adulthood education. CONCLUSIONS: In this prospective study, the association of a risk score of 97 genetic variants with BMI was stronger among those with low compared with high education. This suggests lower education in adulthood accentuates the risk of higher BMI in people at genetic risk.

Maternal and fetal genetic contribution to gestational weight gain.

BACKGROUND: Clinical recommendations to limit gestational weight gain (GWG) imply high GWG is causally related to adverse outcomes in mother or offspring, but GWG is the sum of several inter-related complex phenotypes (maternal fat deposition and vascular expansion, placenta, amniotic fluid and fetal growth). Understanding the genetic contribution to GWG could help clarify the potential effect of its different components on maternal and offspring health. Here we explore the genetic contribution to total, early and late GWG. PARTICIPANTS AND METHODS: A genome-wide association study was used to identify maternal and fetal variants contributing to GWG in up to 10 543 mothers and 16 317 offspring of European origin, with replication in 10 660 mothers and 7561 offspring. Additional analyses determined the proportion of variability in GWG from maternal and fetal common genetic variants and the overlap of established genome-wide significant variants for phenotypes relevant to GWG (for example, maternal body mass index (BMI) and glucose, birth weight). RESULTS: Approximately 20% of the variability in GWG was tagged by common maternal genetic variants, and the fetal genome made a surprisingly minor contribution to explain variation in GWG. Variants near the pregnancy-specific beta-1 glycoprotein 5 (PSG5) gene reached genome-wide significance (P=1.71 × 10-8) for total GWG in the offspring genome, but did not replicate. Some established variants associated with increased BMI, fasting glucose and type 2 diabetes were associated with lower early, and higher later GWG. Maternal variants related to higher systolic blood pressure were related to lower late GWG. Established maternal and fetal birth weight variants were largely unrelated to GWG. CONCLUSIONS: We found a modest contribution of maternal common variants to GWG and some overlap of maternal BMI, glucose and type 2 diabetes variants with GWG. These findings suggest that associations between GWG and later offspring/maternal outcomes may be due to the relationship of maternal BMI and diabetes with GWG.

Genetic risk clustering increases children's body weight at 2 years of age - the STEPS Study.

BACKGROUND: Genetic determinants have an impact on adult weight but the association between genetic determinants and weight at young age is still poorly understood. OBJECTIVE: The objective of this study was to examine the association between genetic risk scores and early growth from birth to 2 years of age. METHODS: Genetic risk scores of 83 adiposity-related or obesity-related single nucleotide polymorphisms (SNPs) (genetic risk score [GRS]83) were calculated for 1278 children. Specific phenotype score for 16 weight-related SNPs (weightGRS) was calculated. Anthropometric data were obtained at birth, 13 months and 2 years of age. RESULTS: The GRS83 was associated with weight at 13 months (ß = 0.080, P = 0.015) and 2 years (ß = 0.080, P = 0.017) of age and with weight gain from birth to 13 months (ß = 0.069, P = 0.036) and to 2 years of age (ß = 0.074, P = 0.028). At 2 years of age, the GRS83 was also associated with weight for height (ß = 0.065, P = 0.046), weight-for-height standard deviation score (SDS) (ß = 0.074, P = 0.022) and body mass index SDS (ß = 0.068, P = 0.045). WeightGRS was associated with higher body weight at 13 months (ß = 0.081, P = 0.014) and 2 years of age (ß = 0.086, P = 0.011). The genetic effect on weight varied from 0.69 to 1.89 kg at 2 years of age according to number of risk alleles. Children with high genetic risk for adiposity were heavier than children with low genetic risk at 2 years of age (12.8 vs. 13.4 kg, P = 0.017). CONCLUSION: The GRS 83 revealed increased genetic risk for higher weight in children already at 13 months and 2 years of age, which may result in increased obesity risk later in life.