The Disease
What IgG4-related disease is, how it develops, and who it affects.
What is IgG4-RD?
IgG4-related disease (IgG4-RD) is an immune-mediated condition that can involve nearly any organ in the body. It causes inflammation and symptoms that can mimic other illnesses, which can delay a clear diagnosis and timely, effective treatment.
IgG4-RD is characterised by mass-forming lesions with a relapsing-remitting course that might lead to organ failure if left untreated. This fibro-inflammatory disorder is named for the accumulation of IgG4-secreting plasma cells in tissues and the increase of IgG4 concentration in the serum of most patients.
First described in 2001 in the setting of autoimmune pancreatitis, IgG4-RD is now known to affect virtually any anatomical district.
Four recognised phenotypes
- Pancreato-hepatobiliary disease
- Retroperitoneal fibrosis, with or without aortitis
- Head and neck limited disease
- Classic Mikulicz's syndrome with systemic involvement
Who does it affect?
Male to female ratio
IgG4-RD predominantly affects middle-aged individuals, with a male to female ratio of approximately 5:1.
Per 100,000 person-years
Based on a 2019 US claims-data analysis, the incidence of IgG4-RD was 1.39 per 100,000 person-years.
Per 100,000 persons (prevalence)
Prevalence of 5.3 per 100,000 persons (US, 2019). True numbers are likely underestimated as many cases go unrecognised.
According to a national epidemiological survey from Japan, the incidence of autoimmune pancreatitis in 2016 was 3.1 cases per 100,000 individuals — but pancreatic involvement represents only one of more than a dozen organs potentially affected by IgG4-RD.
What causes IgG4-RD?
There are no established hereditary risk factors. There are few if any reports of relatives being affected by IgG4-RD, indicating that it is not an inherited condition and carries a negligible risk of parental transmission.
Among environmental factors, an increased incidence of cigarette smoking and exposure to metals, toxins, or poisons — particularly in blue-collar occupations — has been observed in IgG4-RD patients.
The precise mechanisms driving IgG4-RD remain unclear and are under investigation. Aberrant innate and adaptive immunity are considered the main drivers of disease pathogenesis.
How does it present?
The clinical presentation is usually indolent, with signs and symptoms becoming evident over months or years. Most characteristic are pseudotumor-like lesions involving single or multiple organs.
Common
- Autoimmune pancreatitis
- Chronic periaortitis
- Retroperitoneal fibrosis
- Salivary or lacrimal gland swelling
Atypical
- Tubulointerstitial nephritis
- Glomerulonephritis
- Interstitial lung disease
- Pleural and pericardial effusion
Carsten Sørensen
Patient & Treasurer, Denmark
As a co-founder and chair of the federation, I am proud to lead a community advocating for better recognition and care for IgG4-RD.
About the European Federation IgG4-RD
We are the bridge between you, the patient, be it as a direct member or through your own national association and the medical world and wider community. We connect knowledge, compassion, and advocacy across Europe for those affected by IgG4-Related Disease.
