2025 – PAGE 113 – ALLERGY & IMMUNOLOGY
IGA DEFICIENCY
IgA deficiency is extremely common, but 80% of those who have it are asymptomatic. The ones who do have problems usually develop recurrent sinus and pulmonary infections.
HYPER-IGE SYNDROME
Hyper-IgE syndrome is an autosomal dominant disorder associated with impaired neutrophil chemotaxis and extremely high IgE levels. Look for Eosinophilia + Eczema + Elevated levels of IgE. Eczema often starting in the FIRST WEEK OF LIFE. The patient may have recurrent sinus and pulmonary infections (recurrent pneumonias!). Pneumatoceles will often be seen on a chest X-ray after a pneumonia. The patient may also have recurrent “cold” STAPHYLOCOCCUS infections/abscesses/boils (“cold” because there is no surrounding erythema due to neutrophil chemotaxis impairment). He or she can also have lung abscesses. Patients can also have delayed shedding of primary dentition (tEEth) and skeletal/bone problems (e.g., coarse facial features, scoliosis, and fractures).
MNEMONIC: Instead of just saying Hyper-IgE, show your pearly white tEEEth and say Hyper-Ig-EEEEEEE Look at the bold letters above and look for delayed dentition. Also, if you put the two E’s of tEEth on their side, they kind of look like teeth!
COMPLEMENT DEFICIENCIES
GENERAL PEARLS
- Complement can help clear pathogens in multiple ways, including by binding to Ag-Ab complexes and also by binding directly onto some types of bacteria, and thus promoting phagocytosis.
- NEISSERIA MENINGITIDIS (AKA meningococcus or meningococcal disease): Look for recurrent and overwhelming infections due to this bug in children under the age of two (after that age, they have antibodies towards various meningococcal serogroups). NEISSERIA GONORRHEA infections can also be severe.
- CH50: If this is normal, then ALL complement pathways are okay (C1–9).
C1–4 COMPLEMENT DEFICIENCY
C1-C4 complement deficiency may look similar to Agammaglobulinemia (AKA Bruton’s = Boys = antiBodies = Bacterial infections) because this part of the complement system works closely with antiBodies.
C5–9 COMPLEMENT DEFICIENCY
C5–9 complement deficiency has an unusual predilection towards NEISSERIA infections (both MENINGITIDIS and GONORRHEA). Prevent by early meningococcal vaccination, during the first year of life.
(DOUBLE TAKE) C1 ESTERASE DEFICIENCY (HEREDITARY ANGIOEDEMA)
C1 esterase deficiency results in hereditary angioedema, in which there are recurrent episodes of swelling/edema and abdominal pain.
PEARL: These patients do NOT have pruritis.