Protein-truncating variants in BSN are associated with severe adult-onset obesity, type 2 diabetes and fatty liver disease

Obesity is a major risk factor for many common diseases and has a substantial heritable component. To identify new genetic determinants, we performed exome-sequence analyses for adult body mass index (BMI) in up to 587,027 individuals. We identified rare loss-of-function variants in two genes (BSN and APBA1) with effects substantially larger than those of well-established obesity genes such as MC4R. In contrast to most other obesity-related genes, rare variants in BSN and APBA1 were not associated with normal variation in childhood adiposity. Furthermore, BSN protein-truncating variants (PTVs) magnified the influence of common genetic variants associated with BMI, with a common variant polygenic score exhibiting an effect twice as large in BSN PTV carriers than in noncarriers. Finally, we explored the plasma proteomic signatures of BSN PTV carriers as well as the functional consequences of BSN deletion in human induced pluripotent stem cell-derived hypothalamic neurons. Collectively, our findings implicate degenerative processes in synaptic function in the etiology of adult-onset obesity.

Association of tyrosine hydroxylase 01 (TH01) microsatellite and insulin gene (INS) variable number of tandem repeat (VNTR) with type 2 diabetes and fasting insulin secretion in Mexican population

PURPOSE

A variable number of tandem repeats (VNTR) in the insulin gene (INS) control region may be involved in type 2 diabetes (T2D). The TH01 microsatellite is near INS and may regulate it. We investigated whether the TH01 microsatellite and INS VNTR, assessed via the surrogate marker single nucleotide polymorphism rs689, are associated with T2D and serum insulin levels in a Mexican population.

METHODS

We analyzed a main case-control study (n = 1986) that used univariate and multivariate logistic regression models to calculate the risk conferred by TH01 and rs689 loci for T2D development; rs689 results were replicated in other case-control (n = 1188) and cross-sectional (n = 1914) studies.

RESULTS

TH01 alleles 6, 8, 9, and 9.3 and allele A of rs689 were independently associated with T2D, with differences between sex and age at diagnosis. TH01 alleles with ≥ 8 repeats conferred an increased risk for T2D in males compared with ≤ 7 repeats (odds ratio, ≥ 1.46; 95% confidence interval, 1.1-1.95). In females, larger alleles conferred a 1.5-fold higher risk for T2D when diagnosed ≥ 46 years but conferred protection when diagnosed ≤ 45 years. Similarly, rs689 allele A was associated with T2D in these groups. In males, larger TH01 alleles and the rs689 A allele were associated with a significant decrease in median fasting plasma insulin concentration with age in T2D cases; the reverse occurred in controls.

CONCLUSION

Larger TH01 alleles and rs689 A allele may potentiate insulin synthesis in males without T2D, a process disabled in those with T2D.

Global Effect of Modifiable Risk Factors on Cardiovascular Disease and Mortality

BACKGROUND

Five modifiable risk factors are associated with cardiovascular disease and death from any cause. Studies using individual-level data to evaluate the regional and sex-specific prevalence of the risk factors and their effect on these outcomes are lacking.

METHODS

We pooled and harmonized individual-level data from 112 cohort studies conducted in 34 countries and 8 geographic regions participating in the Global Cardiovascular Risk Consortium. We examined associations between the risk factors (body-mass index, systolic blood pressure, non-high-density lipoprotein cholesterol, current smoking, and diabetes) and incident cardiovascular disease and death from any cause using Cox regression analyses, stratified according to geographic region, age, and sex. Population-attributable fractions were estimated for the 10-year incidence of cardiovascular disease and 10-year all-cause mortality.

RESULTS

Among 1,518,028 participants (54.1% of whom were women) with a median age of 54.4 years, regional variations in the prevalence of the five modifiable risk factors were noted. Incident cardiovascular disease occurred in 80,596 participants during a median follow-up of 7.3 years (maximum, 47.3), and 177,369 participants died during a median follow-up of 8.7 years (maximum, 47.6). For all five risk factors combined, the aggregate global population-attributable fraction of the 10-year incidence of cardiovascular disease was 57.2% (95% confidence interval [CI], 52.4 to 62.1) among women and 52.6% (95% CI, 49.0 to 56.1) among men, and the corresponding values for 10-year all-cause mortality were 22.2% (95% CI, 16.8 to 27.5) and 19.1% (95% CI, 14.6 to 23.6).

CONCLUSIONS

Harmonized individual-level data from a global cohort showed that 57.2% and 52.6% of cases of incident cardiovascular disease among women and men, respectively, and 22.2% and 19.1% of deaths from any cause among women and men, respectively, may be attributable to five modifiable risk factors. (Funded by the German Center for Cardiovascular Research (DZHK); ClinicalTrials.gov number, NCT05466825.).

Diabetes and infectious disease mortality in Mexico City

INTRODUCTION

Although higher risks of infectious diseases among individuals with diabetes have long been recognized, the magnitude of these risks is poorly described, particularly in lower income settings. This study sought to assess the risk of death from infection associated with diabetes in Mexico.

RESEARCH DESIGN AND METHODS

Between 1998 and 2004, a total of 159 755 adults ≥35 years were recruited from Mexico City and followed up until January 2021 for cause-specific mortality. Cox regression yielded adjusted rate ratios (RR) for death due to infection associated with previously diagnosed and undiagnosed (HbA1c ≥6.5%) diabetes and, among participants with previously diagnosed diabetes, with duration of diabetes and with HbA1c.

RESULTS

Among 130 997 participants aged 35-74 and without other prior chronic diseases at recruitment, 12.3% had previously diagnosed diabetes, with a mean (SD) HbA1c of 9.1% (2.5%), and 4.9% had undiagnosed diabetes. During 2.1 million person-years of follow-up, 2030 deaths due to infectious causes were recorded at ages 35-74. Previously diagnosed diabetes was associated with an RR for death from infection of 4.48 (95% CI 4.05-4.95), compared with participants without diabetes, with notably strong associations with death from urinary tract (9.68 (7.07-13.3)) and skin, bone and connective tissue (9.19 (5.92-14.3)) infections and septicemia (8.37 (5.97-11.7)). In those with previously diagnosed diabetes, longer diabetes duration (1.03 (1.02-1.05) per 1 year) and higher HbA1c (1.12 (1.08-1.15) per 1.0%) were independently associated with higher risk of death due to infection. Even among participants with undiagnosed diabetes, the risk of death due to infection was nearly treble the risk of those without diabetes (2.69 (2.31-3.13)).

CONCLUSIONS

In this study of Mexican adults, diabetes was common, frequently poorly controlled, and associated with much higher risks of death due to infection than observed previously, accounting for approximately one-third of all premature mortality due to infection.

P3824Body composition and mortality from vascular or metabolic causes among 150,000 participants in the Mexico City Prospective Study

Background

Higher body-mass index is associated with increased mortality from vascular disease, renal disease and other metabolic causes. However, body mass reflects both fat and lean mass, which may have very different effects on risk. We investigated the individual and joint relevance of fat and lean mass to mortality from these causes, using data from the Mexico City Prospective Study.

Methods

Between 1998 and 2004, 150,000 adults from Mexico City were recruited into a prospective study and tracked for cause-specific mortality for 14 years. Fat and lean mass at recruitment were predicted using Mexican-specific anthropometric equations, validated in a subset of participants with additional bio-impedance measures. Cox regression was used to assess the relevance of fat and lean mass at recruitment to mortality from a vascular, renal, or other metabolic cause at ages 35–74 years. Analyses were adjusted for age at risk, sex, residential district, education, recreational physical activity, smoking and alcohol consumption. To avoid reverse causality, analyses excluded those with diabetes or other chronic diseases at recruitment, and deaths in the first 5 years of follow-up. Mortality rate ratios (RRs) relate to the differences per SD of the usual values of various factors or the differences between the top tenth and bottom fifth of the values.

Results

Among 112,923 participants aged 35–74 years, mean (SD) fat mass in men and women was 22.0 (6.4) kgs and 29.4 (7.8) kgs respectively, while mean (SD) lean mass was 54.9 (7.2) kgs and 39.2 (5.0) kgs respectively. In both men and women, equation-predicted fat and lean mass closely matched the bio-impedance values (all r>0.86). Both fat and lean mass were positively and approximately log-linearly associated with mortality from a vascular or metabolic cause. However, the association of lean mass with mortality was more than accounted for by the correlation of lean with fat mass. Hence, after adjustment for fat mass, lean mass was inversely associated with risk. For a given amount of fat mass, the RR for vascular/metabolic mortality comparing those in the top tenth versus bottom fifth of the predicted lean mass was 0.35 (95% CI 0.24–0.52). Conversely, for a given amount of lean mass, the RR comparing those in the top tenth versus bottom fifth of the predicted fat mass was 4.06 (3.06–5.39). The RRs associated with each SD higher fat mass (1.51, 1.40–1.63) or lean mass (0.79, 0.73–0.86) appeared to be little affected by age, sex, or levels of other confounders, and were broadly similar for the major vascular, renal, and other metabolic mortality. The height-adjusted RRs were 1.41 (1.30–1.53) for fat mass and 0.91 (0.82–1.00) for lean mass.

Conclusions

In this Mexican cohort, predicted fat and lean mass had opposing effects on vascular and other metabolic deaths, with no evidence of any thresholds throughout the ranges studied.