Immunology and Allergy

Question 1

What is Nijmegen breakage syndrome (NBS)

• mutation
• phenotype
• infections susceptible to

Answer 1

• Mutation in nibrin (NBN) gene on Ch 8q21) ; Nibrin = DNA repair protein
• Progressive, severe microcephaly, IUGR, short stature, immunodeficiency, ataxia and nystagmus
• recurrent sinopulmonary infections + susceptible to lymphoma
  Radiation hypersenitivity due to reduced DNA repair mechanisms

Question 2

Describe CD40 ligand deficiency

- infections susceptible to

Answer 2

• Hyper IgM
• cryptosporidium infection -> chronic infection leads to cholangiocarcinoma
• increased risk of malignancy (peripheral neuroectodermal tumours of GIT) - (as with all immunodeficiencies)

Question 3

X-Linked lymphoproliferative disease (XLP)

• mutation
• infection susceptible to

Answer 3

• mutation in SAP gene = signalling lymphocyte activation molecule (SLAM) associated protein
• well until infection with EBV –> Fulminant infection in preschool years or lymphoma and dysgamaglobulinaemia

Question 4

What is XMEN?

Answer 4

= X-linked immunodeficiency, magnesium defect, EBV infection and neoplasia

• -> EVB related lymphoma but slow chronic onset
• -> mutation of gene encoding magnesium transport