Clinical and genetic analysis of patients with X-linked hyper-IgM syndrome.

To the Editor : Hyper-immunoglobulin M (IgM) syndromes are characterized by the presence of recurrent infections, low levels of IgG and IgA, and normal to high levels of IgM. The X-linked hyper-IgM (X-HIGM) syndrome is the most frequently observed subtype of hyperIgM syndromes (65–70%) and results from defects in the CD40L gene, which encodes for the CD40 ligand (CD154) (1–3). In this study, a total of six patients from five unrelated families were included; only the parents of patient 5 were consanguineous cousins. The median age at the time of diagnosis was 1.8 years (range, 0.6–2.6 years). The six patients included in this study showed typical characteristics of X-HIGM (Table 1).