Seeing the smoking gun: a sensitive and specific method to visualize loss of the tumour suppressor, fumarate hydratase, in human tissues.

In this issue of the Journal of Pathology, Bardella et al report a method for identifying tumours that lack fumarate hydratase. The approach they use is immunodetection of proteins that have been modified by a non-enzymatic reaction of thiol groups in proteins with fumarate, which is termed succination. Validation included the use of mice with targeted inactivation of fumarate hydratase in the kidney, extensive studies of normal human tissues and examination of over 1000 specimens from human cancers not associated with FH mutations. Detection of protein succination is likely to provide a sensitive and specific method for pathologists to identify the small proportion of papillary renal cell carcinomas that are associated with germline mutations in the FH gene.