Primary B-Cell Immunodeficiencies

Question 1

Which immunodeficiency features a mutation in BTK? What is this enzyme? What’s it’s function?

Answer 1

X-Linked agammaglobulinemia. It plays a role in B-cell maturation.

Question 2

How is X-Linked Agammaglobulinemia diagnosed?

Answer 2

Flow shows no B-cells and there will be no adequate titers to immunizations. Ig will be low. There will be a history of recurrent sinopulmonary infections.

Question 3

How is CVID similar to X-linked agammaglobulinemia? How can you tell them apart?

Answer 3

Similar clinical presentation due to lack of Ig (sinopulmonary infections, enterovirus, giardia.) Different in that B cells are present, but they just won’t differentiate into plasma cells. CVID is also associated with other features (see separate flashcard.)

Question 4

CVID presents in similar fashion to X-linked agammaglobulinemia (Bruton’s) but has several other possible features. Discuss.

Answer 4

Non-caseating granulomas (sarcoid-like)
Sprue-like illness
Autoimmune disease
Lymphomas

Question 5

A 13 year old has PJP infection, immunodeficiency, but does not have HIV/AIDS. He has detectable IgM. Which immunodeficiency might he have?

Answer 5

X-Linked Hyper IgM Syndrome

Question 6

What is the defect causing Hyper-IgM Syndrome?

Answer 6

CD40L defect

Question 7

True or False: An infant diagnosed with transient hypogammaglobulinemia of infancy cannot mount an adequate immunization response.

Answer 7

False. They may have low titers but they do develop proper antibodies to the vaccinations.

Question 8

At what age should you expect a child with transient hypogammaglobulinemia to develop a more normal total immunoglobulin amount?

Answer 8

By 4 years, this condition usually resolves.