LY9 and systemic lupus erythematosus: CD229 was up‐regulated on cells from SLE patients but the genotype of CD229 was not determined in that study.17 The A/G variants of rs509749 SNP are present in nearly equal measure (A = 55%, G = 45%) in the European population whereas in other populations, G is the major allele.31 We genotyped five healthy donors and identified two heterozygotes and three homozygotes, two CD229 Met602 and one CD229 Val602.