immunology - Do you know of any disease where HLA / MHC association discovery has led to better treatment or management?

If we discover an association between a disease and a particular HLA type (MHC class I or class II molecule) then it may provide us with some insight into the disease in a very basic way. However, will it provide us with a therapeutic target? Or second best, will it provide us with information that is useful for diagnosis or management? I am looking for examples. Do you know of any?

The most obvious is in transplantation where one would use HLA typing to match donor to recipient but that is not the same as using knowledge of an HLA type to target, treat, diagnose, prognosticate.