Antibody Response:
Isohemaglutinin levels were normal (above 1/8) in 21 patients (63.6%), and was not evaluated in others.
Anti-HBs antibody was positive in 24 (72.7%) patients, and negative in 6 (18.1%). Four patients were evaluated again after vaccination, two of the patients’s antiHbs results were positive and two of them were still negative after vaccination. Two patients were not evaluated for antiHbs antibody after vaccination.
Treatment: None of the patients with sIgMD required intravenous immunoglobulin (IVIG). Nine patients (27,2%) were given prophylactic antibacterial therapy for recurrent infections.

Primary Immunodeficiency Diseases

Although sIgMD is defined as isolated low levels of IgM with normal levels of IgA and IgG without other defined immunodeficiency, we also evaluated patients with welldefined PID. During follow-up, 13 patients were diagnosed with other types of PID diseases. These were T cell deficiency (n=6), combined immunodeficiency (CID) (n=3), autoimmune lymphoproliferative disease (ALPS) (n=2), chronic granulomatous disease (n=1), congenital neutropenia (HAX-1 gene defect) (n=1). The molecular defects of the patients diagnosed with CID in the follow-up were Serine-threonine kinase-4 (STK4 ) deficiency (n=2), interleukin-2 inducible kinase (ITK ) deficiency (n=1). TwoSTK- 4 deficient patients were initially presented with susceptibility to infection and vasculitis; they got the molecular diagnosis of T cell deficiency approximately 2 years after admission. One patient developed acute EBV-associated lymphoproliferative syndrome. Two patients who were followed up with CID developed non-Hodgkin’s lymphoma over years. Among the two patients died; one died at 22 years of age, had STK 4 gene mutation, lymphoma and amyloidosis; the other patient developed secondary malignancy (acute myeloid leukemia (AML) after treatment for lymphoma, and died at the age of 12 years.