APOE and myeloid sarcoma: For instance, several studies reported that cognitive symptoms are more severe and occur more often in male patients than in female patients.25,42 Moreover, in adult patients with MS, cognitive symptoms seem to be worse with older age of onset.43 Lastly, the apolipoprotein E4 allele (APOE4), a gene associated to the sporadic form of AD, was reported as potential risk factor for more rapid disease progression and cognitive decline in MS, whereas the more common susceptibility genes for MS, such as human leukocyte antigen class II (HLA-II), do not specifically relate to cognition.44