Hyper-IgE Syndrome (HIES)
Introduction And Classification
Hyper-IgE syndromes represent a group of primary immunodeficiency diseases characterised by a strong atopic diathesis, highly elevated serum immunoglobulin E (IgE), and recurrent skin and pulmonary infections. These disorders demonstrate significant genetic heterogeneity.
| Genetic Defect | Inheritance | Associated Syndrome |
|---|---|---|
| STAT3 | Autosomal dominant | Classic Job syndrome |
| DOCK8 | Autosomal recessive | DOCK8 deficiency |
| IL6R / IL6ST | Autosomal recessive / dominant | IL-6 receptor / signal transducer deficiency |
| ZNF341 | Autosomal recessive | ZNF341 deficiency |
| PGM3 | Autosomal recessive | PGM3 deficiency |
Autosomal Dominant Hyper-IgE Syndrome (Job Syndrome)
Pathophysiology
- The condition is caused by heterozygous pathogenic variants in the signal transducer and activator of transcription 3 (STAT3) gene.
- These variants exert a dominant-negative effect resulting in loss of function.
- The genetic defect compromises signaling downstream of multiple receptors.
- Affected pathways include interleukin (IL)-6, type I interferon, IL-22, IL-10, and epidermal growth factor receptors.
- This dysregulation leads to a marked deficiency or complete absence of T-helper type 17 (Th17) cells.
Clinical Manifestations
Patients present with a combination of immunologic and non-immunologic features.
Immunologic Features
- Recurrent staphylococcal skin abscesses are a hallmark.
- These are often described as "cold" abscesses because they lack classical signs of inflammation.
- Early-onset atopic dermatitis or a pruritic pustular dermatosis is common.
- Chronic mucocutaneous candidiasis affects more than 70% of patients.
- Recurrent pneumonias frequently occur and typically result in the formation of pneumatoceles and bronchiectasis.
- Common respiratory pathogens include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Aspergillus, and Pneumocystis jirovecii.
Non-Immunologic Features
- Patients develop characteristic coarse facial features.
- These include a prominent forehead, deep-set wide-spaced eyes, a broad nasal bridge, a wide fleshy nasal tip, and mild prognathism.
- Skeletal and connective tissue abnormalities are prominent.
- Findings include hyperextensible joints, osteoporosis with recurrent minimal-trauma fractures, and scoliosis.
- Delayed shedding of primary teeth is a classic dental finding.
- Vascular anomalies such as coronary and cerebral aneurysms may occur.
Laboratory Evaluation
| Parameter | Typical Findings in STAT3 Deficiency |
|---|---|
| Immunoglobulins | Exceptionally high serum IgE (>2,000 IU/mL), although it may decrease in adulthood. IgG, IgA, and IgM are usually normal. |
| Complete Blood Count | Pronounced blood and sputum eosinophilia are present. |
| Lymphocyte Subsets | Normal percentages of T, B, and natural killer (NK) cells. Decreased memory T cells and absent Th17 cells. |
| Immune Function | Poor specific antibody and cell-mediated responses to neoantigens. |
Autosomal Recessive Hyper-IgE Syndromes
These syndromes typically lack the somatic, skeletal, and dental features seen in classic Job syndrome.
DOCK8 Deficiency
- Pathogenic variants in the DOCK8 gene cause a severe combined immunodeficiency.
- Patients present with early-onset, severe eczema and multiple food allergies.
- There is a marked susceptibility to severe cutaneous viral infections.
- Pathogens include herpes simplex virus, varicella, human papillomavirus, and molluscum contagiosum.
- Patients frequently suffer from recurrent respiratory infections and are susceptible to cancer development, such as squamous cell carcinoma and lymphoma.
- Laboratory findings reveal T-cell lymphopenia, reduced regulatory T cells, low NK cells, and highly elevated IgE.
Management
Medical And Supportive Therapy
- Antimicrobial and antifungal prophylaxis is essential for infection prevention.
- A combination of trimethoprim-sulfamethoxazole (for bacterial and Pneumocystis prophylaxis) and itraconazole (for fungal prophylaxis) is widely recommended.
- Aggressive topical skin care is required to manage eczema and associated cutaneous infections.
- Immunoglobulin replacement therapy may be indicated if there is a documented deficiency in specific antibody production.
Definitive Therapies
- Hematopoietic stem cell transplantation (HSCT) provides a curative option for specific variants.
- It is highly recommended early in life for patients with DOCK8 deficiency to prevent severe long-term complications and malignancy.