Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Selective IgM deficiency ?
    ### Response:
    Selective IgM deficiency or "Selective Immunoglobulin M deficiency (SIgMD) is a rare immune disorder that has been reported in association with serious infections, such as bacteremia. The disorder can occur in babies, children, and adults. It is characterized by isolated absence or deficiency of IgM, normal levels of other immunoglobulins and recurrent infections (especially by Staphylococcus aureus, Streptococcus pneumoniae, Hemophilus influenza).
    