<<Disclaimer: Verify this information before applying it to your situation.>>
 
I would recommend that your brother visit a local dermatologist.  The
diagnosis of DH could be based upon clinical presentation confirmed by
immunofluorescent studies of a punch biopsy of the skin.
 
The immunopathological studies of the biopsy of the skin are the hallmark of
DH.  These biopsies could be sent to any other specialized laboratory.
 
Any questions?
 
Vijay Kumar, Ph.D., FACB