What is IGg4?

Here are some links to find out more:

http://www.uptodate.com/contents/overview-of-igg4-related-disease

http://en.wikipedia.org/wiki/IgG4%E2%80%93related_systemic_disease

http://e-immunohistochemistry.info/web/IgG4-related_systemic_disease.htm

http://www.uptodate.com/contents/overview-of-igg4-related-disease