Scotland has long been known to have a high incidence of MS.49 The reasons for this remain unknown despite long-running speculation.17 50–62 The Scottish northern isles for many decades have been recognised as particularly burdened.63 Our early exploration of genetic results confirms expected findings of an excess of HLA-DRB1*15:01 (OR 3.90, 95% CI: 2.50 to 6.34) in the Scottish MS population. Here, HLA-DRB1 is linked to myeloid sarcoma.