Introduction
Selective IgM deficiency (sIgMD) is a rare form of dysgammaglobulinemia,
It is classified under primary humoral immunodeficiencies and
characterized by low serum level of IgM, normal IgG and IgA levels with
normal T cell numbers and function in the absence of a defined
immunodeficiency. Pathogenesis of sIgMD is unknown, and no genetic or
molecular basis has been defined yet. However, there are some hypothesis
suggesting that it may be due to defective B cell maturation or T cell
dysfunction [1, 2].
The European Society for Immunodeficiencies (ESID) Registry defines
primary selective IgM deficiency (sIgMD) as serum IgM level repeatedly
below 2 standard deviations (<-2SD) of reference levels, and
normal levels of serum IgA, IgG and IgG subclasses, normal vaccination
responses, absence of T cell defects and absence of causative external
factors [3-5]. In another definition, sIgMD was defined as having
low IgM, which is usually lower than 20 mg/dL in infants and children,
or lower than 2SD. Usually, serum IgM levels are lower than10–20 mg/dL.
The levels of other immunoglobulin isotypes are typically normal,
although IgE may be increased [6, 7]. There is no definition for
IgE, and high IgE may be observed in some cases [8]. SIgMD is
observed in both children and adults [9].
Although it may occur in asymptomatic individuals [10], patients
with sIgMD may present with various clinical features. It may associate
with recurrent upper respiratory tract infections (URTI), atopic
manifestations (rhinitis, asthma etc.), autoimmune diseases,
malignancies, and other primary humoral immunodeficiency diseases. There
are several reports in the medical literature including diseases that
may cause decreased IgM levels, such as recurrent infections, autoimmune
diseases (Celiac disease, hemolytic anemia), and different types of
primary immunodeficiency (PID) (thymic hypoplasia, Wiskott Aldrich
syndrome, ataxia telangiectasia, common variable immunodeficiency
(CVID), Bruton agammaglobulinemia and congenital diseases (Bloom
syndrome, Russel silver syndrome, DiGeorge syndrome) [11].
Our aim is evaluation of the demographic features, clinical
presentations, associated diseases and infections of the patients who
are followed up with sIgMD.