PHILADELPHIA – according to research described at the annual meeting of the American Academy of Neurology. Future research will be required to understand the interactions between dietary vitamin D ingestion, sun exposure, pigmentation of sun-exposed skin, seasonal vitamin D concentrations, and the genetic influences of vitamin D pathways with MS risk.
Race, vitamin D status, HLA-DRB1*15 genotype, and place of residence during childhood all affect the risk of MS. The place of residence also can affect exposure to ultraviolet radiation and, thus, dermal pigmentation.
Candice Dunn, a clinical research coordinator at the Children’s Hospital of Philadelphia, and colleagues conducted a prospective study to determine whether HLA-DRB1*15 status, 25-hydroxyvitamin D (25[OH]D) levels measured at baseline, and skin tone are associated with MS outcome in children with ADS. They enrolled 259 children with incident ADS in a multisite study in Toronto and Philadelphia (latitudes 43° to 51°). The investigators measured non–sun-exposed upper inner arm melanin content using the DSM II ColorMeter device. They measured 25(OH)D concentrations in serum obtained within 60 days of symptom onset and compared them with laboratory-reported normative values. Vitamin D insufficiency was defined as 25(OH)D less than 75 nmol/L. Ms. Dunn and colleagues quantified HLA-DRB1*15 alleles using allele-specific polymerase chain reaction amplification. Statistical analysis was performed using Spearman correlation models and Wilcoxon or Kruskal-Wallis tests as appropriate.
In all, 68 children were diagnosed with MS, 191 remained monophasic (monoADS). Approximately 46% of children with MS were HLA-DRB1*15-positive, compared with 29.9% of monoADS children. In addition, children with MS had significantly lower 25(OH)D levels (mean, 45.4 nmol/L) than monoADS children (mean, 61.9 nmol/L) at baseline. Non–sun-exposed skin tone measured in the upper inner arm did not differ between children diagnosed with MS (mean melanin index, 46.4) and monoADS (mean melanin index, 43.5). Furthermore, 25(OH)D levels correlated with upper inner arm melanin index in the MS group, but not in children with monoADS.
Ms. Dunn had nothing to disclose, but various coauthors have received compensation from companies such as Novartis, Merck, Teva, Celgene, and Genentech.
SOURCE: Dunn C et al. AAN 2019, Abstract S19.007.