Providing further evidence that low 1,25(OH)2D levels may have an important influence on MS risk is the recent discovery in multiplex Canadian families of the first rare variants within the CYP27B1 gene that are associated with an increased risk of MS onset (Peto OR = 4.7 (95% confidence interval CI, 2.3–9.4; p = 5 × 10−7)) [136]. Here, CYP27B1 is linked to myeloid sarcoma.