Using the approach of GRS to aggregate the effects of candidate loci, our dataset does not exhibit evidence for modest effects in PICALM, CR1, CLU or ZNF224. Additional fine mapping will be required to determine whether rs8192708 is in fact the causal variant and whether PCK1 is the causal gene for the observed association with brain atrophy in MS. Here, CR1 is linked to myeloid sarcoma.