Immunodeficiencies

Question 1

X-Linked hyper IgM syndrome

Answer 1

• CD40L deficiency (on T cells)
• Failure of B cell maturation from primary to secondary
• Low IgG and IgA, raised (or normal) IgM
• Recurrent bacterial infections
• Presents age 3-6 months

Question 2

Causes of immunodeficienies

Answer 2

Physiological (infancy)
Secondary
Primary (X linked)

Question 3

Common gamma chain deficiency

Answer 3

X-Linked SCID

Absent T cells
B cells present but non-functional

Question 4

JAK 3 Deficiency

Answer 4

Autosomal recessive

Absent T cells
B cells present but non-functional

Question 5

RAG 1/2 Deficiency

Answer 5

Autosomal recessive

No T cells and B cells

Question 6

DiGeorge Syndrome

Answer 6

Autosomal dominant

Ch22 deletion

Full phenotype: Congenital defects, Absent parathyroids, Cleft palate, Thymic aplasia

Question 7

Terminal complement deficiency

Answer 7

Terminal complement components=C5-C9

Leads to speific susceptibility to Neisseria Species

Question 8

XLA

Answer 8

• X-linked agammaglobulinaemia/Bruton’s disease
• a prototype antibody deficiency syndrome
• Signalling via Bruton’s tyrosine kinase (btk) required for signal transduction at pro-B stage
• Maturation arrest occurs if absent: no heavy chain rearrangement, no B cells leave marrow, no immunoglobulin production