The 782C → T (T254M) XHIM Mutation: Lack of a Tight Phenotype-Genotype Relationship

To the Editor: In a recent report in Blood, Seyama et al[1][1]described 28 unique mutations of the CD40 ligand ( CD40L ) gene in 45 X-linked hyper IgM syndrome (XHIM) patients from 30 unrelated families. Generally, peripheral blood mononuclear cells (PBMC) are screened for CD40L expression after