Selective IgM deficiency

What it is

From: Orphanet

A rare primary immunodeficiency characterized by recurrent and/or invasive bacterial, viral, and fungal infections, associated with low to absent blood IgM levels, while IgG, IgG subclasses, and IgA levels, as well as IgG antibody response to vaccinations, are normal. Patients may also present allergic diatheses, and the prevalence of autoimmune diseases is increased.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Decreased circulating total IgM · Very frequent (99-80%)

An abnormally decreased level of immunoglobulin M (IgM) in blood.

Recurrent infections · Very frequent (99-80%)

Increased susceptibility to infections as manifested by repeated bouts of infection.

Recurrent respiratory infections · Very frequent (99-80%)

An increased susceptibility to respiratory infections as manifested by a history of recurrent respiratory infections.

Severe infection · Very frequent (99-80%)

A type of infection that is regarded as a sign of a pathological susceptibility to infection because of unusual severity or intensity of the infection.

Allergy · Frequent (79-30%)

An allergy is an immune response or reaction to substances that are usually not harmful.

Autoimmunity · Frequent (79-30%)

The occurrence of an immune reaction against the organism's own cells or tissues.

Decreased specific antibody response to vaccination · Frequent (79-30%)

A reduced ability to synthesize postvaccination antibodies against toxoids and polysaccharides in vaccines, as measured by antibody titer determination following vaccination.

Recurrent pneumonia · Frequent (79-30%)

An increased susceptibility to pneumonia as manifested by a history of recurrent episodes of pneumonia.

Recurrent sinusitis · Frequent (79-30%)

A recurrent form of sinusitis.

Recurrent upper respiratory tract infections · Frequent (79-30%)

An increased susceptibility to upper respiratory tract infections as manifested by a history of recurrent upper respiratory tract infections (running ears - otitis, sinusitis, pharyngitis, tonsillitis).

Allergic rhinitis · Occasional (29-5%)

It is characterized by one or more symptoms including sneezing, itching, nasal congestion, and rhinorrhea.

Antinuclear antibody positivity · Occasional (29-5%)

The presence of autoantibodies in the serum that react against nuclei or nuclear components.

Asthma · Occasional (29-5%)

Asthma is characterized by increased responsiveness of the tracheobronchial tree to multiple stimuli, leading to narrowing of the air passages with resultant dyspnea, cough, and wheezing.

Atopic dermatitis · Occasional (29-5%)

Atopic dermatitis (AD) or atopic eczema is an itchy, inflammatory skin condition with a predilection for the skin flexures. It is characterized by poorly defined erythema with edema, vesicles, and weeping in the acute stage and skin thickening (lichenification) in the chronic stage.

Other findings in the same source

From: Orphanet

Additional reported features include Autoimmune thrombocytopenia (Occasional (29-5%)); Bronchiectasis (Occasional (29-5%)); Cellulitis (Occasional (29-5%)); Chronic diarrhea (Occasional (29-5%)); Chronic fatigue (Occasional (29-5%)); Chronic oral candidiasis (Occasional (29-5%)); Chronic sinusitis (Occasional (29-5%)); Cutaneous abscess (Occasional (29-5%)); Decreased proportion of CD4-positive T cells (Occasional (29-5%)); Decreased proportion of transitional B cells (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

All ages

Frequency and the population described

From: Orphanet

Point prevalence: Unknown; Worldwide; Class only.

Which doctor should you see?

The suggested department for discussing Selective IgM deficiency is Allergy and Immunology, with a allergist / clinical immunologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the history suggest an allergy, an immune problem or another explanation?
• How would any proposed allergy or immune test change care?
• Is an individual emergency plan needed, and who should understand it?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Selective IgM deficiency. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.