Relationship Between Skin Tone and Pediatric-Onset Multiple Sclerosis (MS)

Thursday, May 31, 2018
Exhibit Hall A (Nashville Music City Center)
Candice L Dunn, BSc , Children's Hospital of Philadelphia, Philadelphia, PA
Carmen Yea, MSc , The Hospital for Sick Children, Toronto, ON, Canada
Heather E Hanwell, PhD , Neurosciences and Mental Health, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
E. Ann Yeh, MD, MA, FRCPC, Dip ABPN , Neurology, The Hospital for Sick Children, Toronto, ON, Canada
Ruth Ann Marrie, MD, PhD, FRCPC , Department of Medicine, University of Manitoba, Winnipeg, MB, Canada
Amit Bar-Or, MD , University of Pennsylvania, Philadelphia, PA
Neda Ebrahimi, PhD , The Hospital for Sick Children, Toronto, ON, Canada
Brenda Banwell, MD , Children's Hospital of Philadelphia, Philadelphia, PA
Julia O'Mahony, BSc , Hospital for Sick Children, Toronto, ON, Canada

Background: The risk of multiple sclerosis (MS) varies by geographical location, particularly residence during childhood, with an inverse relationship to ambient ultraviolet radiation. Specifically, fair skin tone and limited evidence of sun exposure associate with higher rates of MS. 

Objectives: To determine whether skin tone, as measured by objective and subjective tools, is associated with MS among children who experience acquired demyelinating syndromes (ADS). 

Methods: Participants were enrolled in a multi-site prospective Canadian study consisting of children diagnosed with ADS between 2004 and 2017; skin tone assessments of an unexposed area (upper inner arm) were performed between 2010 and 2017 at Calgary and Toronto sites. Children with MS were compared to those with monophasic (mono) ADS using: 1) objective measurements of melanin quantified using the DSM II Colorimeter; 2) self-reported skin tone according to categorical descriptions (fair, medium, olive, dark); 3) self-reported race and; 4) self-reported skin tone based on a 10-point numerical color panel. Between-group comparisons were performed using χ2 tests, Fisher’s exact tests, and Wilcoxon or Kruskal-Wallis tests as appropriate.

Results: Among the 107 participants, children with MS (n=42) did not differ from those with monoADS (n=65) according to melanin measurements obtained using the DSM II Colorimeter (p=0.98) and self-reported skin tones obtained using categorical descriptions [7 of 36 (19%) MS and 11 of 53 (21%) monoADS reported ‘fair ’ skin tone; p=0.25]. However, children with MS differed from those with monoADS in terms of self-reported race (p=0.03), with a higher representation of non-white children in the MS group. Self-reported skin tone according to the 10-point numerical color panel also differed between groups [median (IQR) 5 (4-8) MS and 6 (4-7) monoADS; p= 0.01] for which lower numbers represent lighter skin tones. 

Conclusions: In Canada, most of the population resides within a narrow latitudinal zone (43°-51°), and thus shares a similar UV exposure opportunity. In this environment, children with ADS are more likely to be diagnosed with MS if they report a non-white race and lighter skin tone. However, melanin content did not distinguish groups, suggesting that factors other than UV absorption, such as genetic risk determinants, dermal synthesis of vitamin D, diet, and other factors are likely contributing to the difference in outcome.