Objectives: To compare Hispanic Whites (HW) and Non-Hispanic Whites (NHW) in various features of clinical presentation of MS, interferon response, the development of disability, and genetic burden for established MS risk alleles.
Methods: HW (n=287) and NHW (n=275) MS cases were ascertained through our MS clinic and through patient outreach efforts that serve the Miami area. A detailed race/ethnicity history was established spanning three generations. Clinical disease characteristics were obtained through a review of the medical records of participants. Genotyping on a custom Illumina chip dubbed the 'Immunochip' provided the genotypes used to calculate the MS Genetic Burden (MSGB) score.
Results: We observed a significant difference in diagnostic lag (time between the first symptom and diagnosis) between HW and NHW, attributed to differences in the source of ascertainment between the two groups. Age at onset was marginally significant (P-value = 0.07), while the symptoms at onset did not significantly differ in the two groups. However, HW patients presented with a significantly lower frequency of motor weakness (P-value = 0.01), ataxia (P-value = 0.02), and bladder disturbance (P-value = 0.004) during the course of illness than NHW. Differences in MSGB were marginally significant (P-value = 0.06), and are explained by the differences in HLA DRB1 alleles in the two populations. Disease progression as measured by the EDSS was not significantly associated with race/ethnicity. Lastly, HW were observed to respond to interferon more favorably than NHW, an association which persists after adjusting for the source of ascertainment (P-value = 0.02).
Conclusions: HW with primarily Caribbean ancestry living in the USA are more likely to experience symptoms of motor weakness, ataxia and bladder disturbance than NHW. Interferon treatment is more effective in HW compared to NHW.