Reduced serum concentrations of 25-hydroxy vitamin D in children with autism: relation to autoimmunity

Abstract

Background: Aside from the skeletal health affection, vitamin D deficiency has been implicated as a potential environmental factor triggering for some autoimmune disorders. Vitamin D might play a role in the regulation of the production of auto-antibodies. Immunomodulatory effects of vitamin D may act not only through modulation of T-helper cell function, but also through induction of CD4(+)CD25(high) regulatory T-cells. We are the first to investigate the relationship between serum levels of 25-hydroxy vitamin D and anti-myelin-associated glycoprotein (anti-MAG) auto-antibodies in autistic children.

Methods: Serum levels of 25-hydroxy vitamin D and anti-MAG auto-antibodies were measured in 50 autistic children, aged between 5 and 12 years, and 30 healthy-matched children. Serum 25-hydroxy vitamin D levels 10-30 ng/mL and < 10 ng/mL were defined as vitamin D insufficiency and deficiency, respectively.

Results: Autistic children had significantly lower serum levels of 25-hydroxy vitamin D than healthy children (P < 0.001) with 40% and 48% being vitamin D deficient and insufficient, respectively. Serum 25-hydroxy vitamin D had significant negative correlations with Childhood Autism Rating Scale (P < 0.001). Increased levels of serum anti-MAG auto-antibodies were found in 70% of autistic patients. Serum 25-hydroxy vitamin D levels had significant negative correlations with serum levels of anti-MAG auto-antibodies (P < 0.001).

Conclusions: Vitamin D deficiency was found in some autistic children and this deficiency may contribute to the induction of the production of serum anti-MAG auto-antibodies in these children. However, future studies looking at a potential role of vitamin D in the pathophysiology and treatment of autism are warranted.

Figure 1

Serum levels of 25-hydroxy vitamin D in the studied children. The boxes enclose the interquartile range (IQR), which are between the 25th and 75th percentiles. The horizontal line inside the box represents the median and the whiskers represent the non-outlier (between 1.5 and 3 IQR) or extreme (more than 3 IQR) maximum and minimum values of serum 25-hydroxy vitamin D.

Figure 2

Serum levels of anti-MAG auto-antibodies in the studied children. Anti-MAG, anti-myelin-associated glycoprotein antibodies; BTU, Buhlmann titre unit.

Figure 3

Negative correlations between serum levels of 25-hydroxy vitamin D and anti-MAG auto-antibodies in children with autism. Anti-MAG, anti-myelin-associated glycoprotein antibodies; BTU, Buhlmann titre unit.