IgA and IgG Hypogammaglobulinemia Is a Constitutive Feature in Most Waldenstrom’s Macroglobulinemia Patients and May Be Related to Mutations Associated with Common Variable Immunodeficiency Disorder (CVID)

Background: Hypogammaglobulinemia of the “uninvolved” immunoglobulins is commonly observed in Waldenstrom’s macroglobulinemia (WM), and has often been attributed to disease-related suppression. However, there is a paucity of information related to the pathogenesis of hypogammaglobulinemia in these disorders.

Methods: We evaluated the incidence of IgA and IgG hypogammaglobulinemia in 207 patients with WM, and addressed the impact of therapy and response on IgA and IgG levels for 93 of these patients who required subsequent treatment. We also performed extensive sequence analysis of the promoter, all exonic, and flanking intronic regions from peripheral blood of 19 untreated WM patients who demonstrated IgA and/or IgG hypogammaglobulinemia for 8 genes often observed in common variable immunodeficiency disorders (CVID) and B cell deficiency i.e. AICDA, BTK, CD40, CD154, NEMO(IkBkG), TACI, SH2D1A, UNG.

Results: At baseline, 120/207 (58.0%), 131/207 (63.3%), and 102/196 (49.3%) patients had abnormally low levels of serum IgG (<700 mg/dL), IgA (<70 mg/dL), or both, respectively. No correlation between baseline bone marrow disease involvement and immunoglobulin levels was observed. With a median follow-up of 12 months following completion of therapy, IgA and/or IgG levels remained abnormally low for 92.1% and 87.3% of responding patients, respectively, including those who achieved a complete remission. Sequence analysis of the NEMO and CVID gene panel demonstrated intronic variation at position c.1056-6T>C (n=2) and a hemizygous missense mutation at codon 113 for NEMO (n=1), and a heterozygous missense mutation at codon 142 in UNG (n=1).

Conclusions: The results of these studies demonstrate that IgA and IgG hypogammaglobulinemia is a constitutive feature of patients with WM, which neither correlates with, nor is impacted by disease burden, despite therapeutic intervention and response. The results also suggest that patients with WM may harbor sequence mutations, which may be a contributor to the pathogenesis and/or morbidity of WM.