Fluctuations of MS births and UV-light exposure

BACKGROUND

Patients with multiple sclerosis (MS) are more frequently born in spring when compared to autumn. Fluctuation of UV-light has been hypothesized to drive this phenomenon.

AIM

To assess the correlation between fluctuation of sunlight and birth season in persons with MS.

METHODS

For this record-linkage study, we collected from the international MSBase and the Italian MS iMed-web databases the dates of birth of 11,415 patients with MS from 36 centres from 15 countries worldwide and compared these to dates of live-births from national registries. From all participating sites, we collected data on UV-light fluctuation and assessed its correlation with seasonal fluctuation in MS births.

RESULTS

Compared with the reference cohort, an increased proportion of persons with MS were born in spring and a decreased proportion in autumn (odds ratio (OR) to be born in spring versus autumn = 1.158, χ² = 36.347, P < 0.001). There was no significantly increased fluctuation of MS births with increased quartile of ambient UV-light fluctuation (Ptrend = 0.086).

CONCLUSION

Seasonal fluctuation of MS births as found in this worldwide cohort of patients with MS did not correlate with variation in seasonal fluctuation of UV-light. Most likely, it results from a complex interplay between fluctuation of sunlight, behavioural factors, other environmental factors and (epi)genetic factors.

Genome-wide association study of multiple sclerosis confirms a novel locus at 5p13.1

Multiple Sclerosis (MS) is the most common progressive and disabling neurological condition affecting young adults in the world today. From a genetic point of view, MS is a complex disorder resulting from the combination of genetic and non-genetic factors. We aimed to identify previously unidentified loci conducting a new GWAS of Multiple Sclerosis (MS) in a sample of 296 MS cases and 801 controls from the Spanish population. Meta-analysis of our data in combination with previous GWAS was done. A total of 17 GWAS-significant SNPs, corresponding to three different loci were identified:HLA, IL2RA, and 5p13.1. All three have been previously reported as GWAS-significant. We confirmed our observation in 5p13.1 for rs9292777 using two additional independent Spanish samples to make a total of 4912 MS cases and 7498 controls (ORpooled = 0.84; 95%CI: 0.80–0.89; p = 1.36×10-9). This SNP differs from the one reported within this locus in a recent GWAS. Although it is unclear whether both signals are tapping the same genetic association, it seems clear that this locus plays an important role in the pathogenesis of MS.

Relevance of interleukin 1 receptor antagonist intron 2 polymorphism in Italian MS patients

The A1/A1 genotype of the anti-inflammatory cytokine interleukin 1 receptor antagonist (IL-1Ra) polymorphism was more frequent in 339 Italian MS patients than in healthy controls (HCs) (odds ratio = 1.83). A more aggressive disease course was also associated with A1+ genotypes and might reflect the reduced ability of mononuclear cell cultures of A1+ HCs to produce IL-1Ra. We conclude that an IL-1Ra gene polymorphism is associated with occurrence of disease and clinical course variability in Italian MS patients.

Occurrence and clinical relevance of an interleukin-4 gene polymorphism in patients with multiple sclerosis

An epistatic gene interaction has been advocated to explain disease susceptibility in multiple sclerosis (MS). Cytokine genes are possible candidates due to the central role played by cytokines in the regulation of the immune-mediated pathogenetic process leading to central nervous system demyelination in these patients. Since interleukin (IL)-4 gene polymorphisms have been associated with immune-mediated diseases, we have analysed the relationship between a variable number of tandem repeat polymorphism of the IL-4 gene and clinical and physiological features of 256 sporadic MS patients and 146 healthy controls. Genotype frequencies were similar between the MS group and healthy controls. However, in MS patients a positive and significant correlation (r = 0.91; p < 0.001) was found between the carriage rate of the IL-4 B1 allele (from 0.21 to 0.36) and age of disease onset. No association was found between IL-4 alleles and disease progression, sex or ethnic background of the patients. Our results show that the IL-4 B1 allele is associated with late onset of MS and therefore might represent a modifier of age of onset rather than a susceptibility factor for patients with MS.