Functional antibody deficiency in a patient with type I Gaucher disease

Gaucher disease (GD), the most common lysosomal storage disorder, demonstrates an autosomal recessive pattern of inheritance. The genetic defect in GD leads to decreased production of the lysosomal enzyme glucosylceramide hydrolase, thereby resulting in the deposition of glucosylceramide sphingolipids within multiple organ systems. Although the precise mechanisms remain unclear, GD is usually associated with chronic antigenic stimulation and hyperimmunoglobulinaemia. We report a novel case of type I GD coexisting with relatively low serum immunoglobulins, impaired antibody production, and recurrent bacterial infections in a 62-year-old male. The patient had been diagnosed with GD 30 years previously and had subsequently started enzyme replacement therapy. Since being diagnosed with GD, the patient had suffered from repeated episodes of acute bronchitis and a recent severe bout of community-acquired pneumonia that required a lengthy hospitalization. On our initial evaluation, the patient had laboratory testing that demonstrated: decreased serum IgG, IgG2, and IgA levels; reduced absolute CD3(+)/CD4(+), CD3(+)/CD8(+), and lymphocyte counts; low IgG titres to pneumococcal polysaccharide vaccine; and decreased anti-tetanus antibodies. Lymphocyte function analysis demonstrated a normal response to phytohaemagglutinin, and decreased responses to concanavalin A and pokeweed mitogen. Repeat testing after 6 months revealed normal serum immunoglobulin levels and mitogenic responses. Although the explanation for our observed transient hypogammaglobulinaemia remains unclear, this patient's clinical constellation (i.e. repeated infections, hypogammaglobulinaemia and lymphopenia, decreased post-vaccination titres, and impaired responses to some mitogens) shares overlapping features with common variable immunodeficiency (CVID).