In/exclusion criteria of the SIMcal study

In order to be eligible to participate in the SIMcal study, a subject must meet al of the following criteria:

1. Informed consent for participation in the ESID registry.

2. Fulfill the ESID Registry Clinical Criteria for 'selective IgM deficiency', demanding a serum IgM level <2SDs below age-adjusted means in children and adults with normal IgG and IgA serum levels and absence of clinical signs suggesting a T-cell defect, and – if determined – normal IgG subclasses, normal T-cell subsets and function, and normal IgG antibody response to vaccinations (see ESID website).