P2RX7 and myeloid sarcoma: Genome-wide associated studies (GWAS) of patients with MS (International Multiple Sclerosis Genetics Consortium, 2007; Australia and New Zealand Multiple Sclerosis Genetics Consortium, 2009; International Multiple Sclerosis Genetics Consortium, 2011, 2013, 2018) identified multiple gene alleles associated with higher risk of MS but none of the highly polymorphic P2X7 genes.