AbstractAtopic dermatitis (AD) patients have been observed to have lower vitamin D levels. Previous studies have found little evidence that vitamin D levels causally influence the risk of AD, but the reverse direction has not yet been investigated.Here we used Mendelian Randomization to assess the causal relationship between AD and serum vitamin D levels, using genetic data from the most recent GWA studies of vitamin D and AD.There was little evidence for vitamin D levels causally influencing AD risk (odds per standard deviations increase in log-transformed vitamin D levels =1.233, 95% CI 0.927 to 1.639, P-value =0.150). However, genetic liability for AD raises serum vitamin D levels by 0.043 (95% CI 0.017 to 0.069) standard deviations per doubling of odds of disease (P-value =0.001). The AD-associated filaggrin (FLG) mutation R501X appears to show a particularly strong relationship with vitamin D. However, the relationship between AD and vitamin D holds when R501X is omitted (0.018, 95% CI 0.004 to 0.031, P-value =0.008).We found evidence that AD is causally associated with an increase in serum vitamin D levels. Whilst the AD-associated FLG gene has a particularly strong relationship with vitamin D, other AD SNPs show a consistent direction of effect, suggesting that AD more generally influences serum vitamin D levels.
Hypogammaglobulinemia Prevelance in Children with Atopic Dermatitis and the Relationship Between Immunoglobulin Levels and Eczema Severity
