PATH - B-cell disorders

Question 1

X-linked (Bruton)

agammaglobulinemia

Answer 1

X-linked recessive
(INC in Boys)

Defect in *BTK, a tyrosine
kinase gene–>no *B-cell
maturation

Recurrent bacterial and
enteroviral infections after *6 months (DEC maternal IgG)

• Absent B cells in peripheral blood
• DEC Ig of all classes
• Absent/scanty lymph nodes and tonsils

Question 2

Selective IgA deficiency

Answer 2

Unknown

Most common 1° immunodeficiency

Majority Asymptomatic

Can see Airway and GI
infections, Autoimmune
disease, Atopy, Anaphylaxis to IgA-containing products.

*DEC IgA with normal IgG, IgM levels

Question 3

Common variable

immunodeficiency

Answer 3

Defect in B-cell differentiation

Can be acquired in 20s–30s

INC risk of autoimmune disease, bronchiectasis, lymphoma, sinopulmonary infections

• DEC plasma cells
• DEC immunoglobulins