IgG-subclass and/or antipolysaccharide antibody deficiency.

Patients with a primary immunodeficiency (PID) have an intrinsic defect in
their immune system that becomes apparent at birth, or later in life with too
many, too frequent, unusual, and/or difficult-to-treat infections. The
awareness concerning PIDs is low, and consequently they are not always
recognized, leading to a diminished quality of life caused by increased
morbidity, higher costs of health care for these patients, more time not spent
in school and work, and ultimately higher costs for the society as a whole, and
sometimes also higher mortality. IgG-subclass and antipolysaccharide
antibodydeficiency comprise the largest group of patients. Little is known
about the prevalence, clinical presentation, therapy, and prognosis in these
patients. It is likely that an early diagnosis of IgG-subclass and/or
antipolysaccharide antibodydeficiency will improve long-term prognosis, but
this is not proven, and it is not clear whether there is a difference between
subgroups of patients. This observational cohort study can help to answer these
questions.

Primary: To provide insight in the prevalence of diagnosed cases of
IgG-subclass and/or antipolysaccharide antibodydeficiency in Dutch children.
Secondary: To provide insight in the diagnostic process, the clinical
presentation, the therapies used by different doctors, and the prognosis of
IgG-subclass and/or antipolysaccharide antibodydeficiency.

Prospective observational cohortstudy using the NSCK-system. After diagnosis,
the pediatrician includes the patient, and answers a digital questionaire (all
patients together form the basic study population Group 0). If informed consent
is given, the patient will be followed either by a yearly questionaire for the
pediatrician and general practioner (Group 1) or by additionally answering
questions about symptoms weekly by the parents and/or patient (depending on
his/her age) during 2 years.

The burden for patients and/or their parents (depending on age) is negligible
in Groups 0 and 1. The burden for patients and/or their parents (depending on
age) in Group 2 is very limited; it concerns a weekly digital diary which will
cost only a few minutes each week. The study will lead to greater insight in
IgG-subclass and antipolysaccharide antibodydeficiency, which could lead to
better quality of care, and probably less or at least later complications for
present and future patients with these conditions. Because the primary aim is
to define the prevalence of IgG-subclass and antipolysaccharide
antibodydeficiency in children, it can only be performed in patients < 18 years
of age.