Selective IgM deficiency

Selective IgM deficiency (also called selective immunoglobulin M deficiency or SIgMD) is a rare immune system disorder in which the body produces abnormally low levels of immunoglobulin M (IgM), one of the five main types of antibodies. IgM is the first antibody your immune system makes when it encounters a new infection, so having too little of it can leave you more vulnerable to certain germs. People with this condition often experience repeated infections, particularly of the respiratory tract (such as sinusitis, bronchitis, and pneumonia), skin infections, and sometimes serious bloodstream infections. Some individuals may also develop autoimmune conditions, where the immune system mistakenly attacks the body's own tissues, or allergic diseases like asthma and eczema. The severity of selective IgM deficiency varies widely. Some people have frequent, severe infections that significantly affect their quality of life, while others may have very mild symptoms or even no symptoms at all and are only discovered through routine blood work. The condition can occur on its own (primary) or alongside other medical conditions (secondary). Diagnosis is based on blood tests showing low IgM levels while other immunoglobulin classes (IgG and IgA) remain normal. Treatment focuses on managing and preventing infections. This may include prompt use of antibiotics when infections occur, and in some cases, preventive (prophylactic) antibiotics for people who get infections very frequently. Immunoglobulin replacement therapy, which is commonly used for other antibody deficiencies, is not typically effective for selective IgM deficiency because standard immunoglobulin preparations contain mostly IgG rather than IgM. Vaccination is encouraged to help boost other parts of the immune response. Research into the underlying causes and better treatments is ongoing.

Bring these to your next appointment

• Q1.How severe is my IgM deficiency, and what does that mean for my risk of infections?,Should I be on preventive antibiotics, and if so, for how long?,Are there any vaccines I should receive or avoid?,How often should I have my immunoglobulin levels and immune function checked?,What signs of infection should prompt me to seek urgent medical care?,Could my IgM deficiency be related to any other immune or autoimmune condition?,Should my family members be tested for immune deficiencies?

Common questions about Selective IgM deficiency

Related conditions

Other rare diseases commonly researched alongside Selective IgM deficiency.

• Transient hypogammaglobulinemia of infancy→