Genetics support childhood adiposity and type 1 diabetes link
medwireNews: Genetic variants associated with childhood body mass index (BMI) correlate with the risk for type 1 diabetes, suggests an analysis of genome-wide association studies (GWAS).
The incidence of type 1 diabetes is rising globally, yet the reasons for this increase remain unclear and cannot be explained by heritability alone, write Tove Fall (Uppsala University, Sweden) and fellow researchers in PLOS Medicine.
They used GWAS data to create a genetic instrumental variable of 23 single nucleotide polymorphisms (SNPs) associated with childhood adiposity and extracted summary level results for its association with type 1 diabetes from data on 5913 children with onset of the condition before 17 years of age and 8828 reference children without type 1 diabetes.
Using inverse-variance weighted Mendelian randomization, the researchers estimated that a genetically predicted increase in childhood BMI of 1 standard deviation is associated with a 32% increased risk for type 1 diabetes.
A significant association remained in further analyses correcting for pleiotropy bias (odds ratio [OR]=2.76) and genetic associations with potential confounders, including birthweight, smoking, and years of education (OR=1.30), and when the genetic variants were restricted to a smaller set of 13 SNPs (OR=1.55).
“This study provides genetic support for a link between childhood adiposity and [type 1 diabetes] risk, which could help explain part of the increase in [type 1 diabetes] rates,” say the researchers.
They note, however, that the results are conditional on Mendelian randomization assumptions being satisfied, and point out that causal inference is limited by the fact that the effects of the genetic variants on type 1 diabetes risk could be via mechanisms other than adiposity.
The results support previous findings from observational studies and “reinforce the need to address rising childhood overweight and obesity rates, whose adverse consequences in adulthood pose serious challenges to personal and population health,” the team concludes.
By Catherine Booth
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