As recognition of<unk>  is relatively recent, there are limited studies on its epidemiology. It is therefore difficult to make an accurate estimation of prevalence. Furthermore, age of onset is almost impossible to estimate; age at diagnosis is frequently misused as the age of onset. A 2011 study estimated the incidence of<unk>  in Japan at 2.8–10.8/million population, with a median age of onset of 58 years.
IgG4-related disease
IgG4-related skin disease
Anti-IgLON5 disease
IgA vasculitis
Isolated primary immunoglobulin M deficiency
Antisynthetase syndrome
Undifferentiated connective tissue disease
Leukotriene receptor antagonist-associated Churg–Strauss syndrome