This study used 3 genetic variants in the genome, which are associated with vD levels, and showed that a genomic proxy of high vD levels decreases the risk of children getting MS. This confirms other epidemiological evidence showing that higher levels of vD levels reduce your risk of getting MS.
In addition to vD the investigator's extended the Mendelian randomisation method to confirm that genetic factors predicting a high body mass index (BMI) increased your risk of getting MS. This analysis suggests that these two factors, vD and BMI, are independent of each other and are in the causal pathway of MS.
How do we keep our children thinned and tanned or at least vD replete.
Gianfrancesco et al. Evidence for a causal relationship between low vitamin D, high BMI, and pediatric-onset MS. Neurology. 2017 Mar 29. doi: 10.1212/WNL.0000000000003849
OBJECTIVE: To utilize Mendelian randomization to estimate the causal association between low serum vitamin D concentrations, increased body mass index (BMI), and pediatric-onset multiple sclerosis (MS) using genetic risk scores (GRS).
METHODS: We constructed an instrumental variable for vitamin D (vitD GRS) by computing a GRS for 3 genetic variants associated with levels of 25(OH)D in serum using the estimated effect of each risk variant. A BMI GRS was also created that incorporates the cumulative effect of 97 variants associated with BMI. Participants included non-Hispanic white individuals recruited from over 15 sites across the United States (n = 394 cases, 10,875 controls) and Sweden (n = 175 cases, 5,376 controls; total n = 16,820).
RESULTS: Meta-analysis findings demonstrated that a vitD GRS associated with increasing levels of 25(OH)D in serum decreased the odds of pediatric-onset MS (odds ratio [OR] 0.72, 95% confidence interval [CI] 0.55, 0.94; p = 0.02) after controlling for sex, genetic ancestry, HLA-DRB1*15:01, and over 100 non-human leukocyte antigen MS risk variants. A significant association between BMI GRS and pediatric disease onset was also demonstrated (OR 1.17, 95% CI 1.05, 1.30; p = 0.01) after adjusting for covariates. Estimates for each GRS were unchanged when considered together in a multivariable model.
CONCLUSIONS: We provide evidence supporting independent and causal effects of decreased vitamin D levels and increased BMI on susceptibility to pediatric-onset MS.