Subtypes

Just read an interesting article in the LA Times on autoimmune diseases. There was one section where scientists are discussing that they now believe autoimmune diseases have SUBTYPES, which can explain the range of symptoms we may all have for the same condition. Here’s a section:
“ In one study, an international team used tiny samples of patients’ joint tissue to identify six inflammatory subtypes of rheumatoid arthritis based on patterns of cells, how they clustered and their activity.”
Apparently this is now being used to better target treatment.
Has anyone heard of this?