The diagnosis of Flammer's syndrome is primarily based on the patient's history with its typical features as well as the findings of nail fold capillaroscopy. This test shows an excessive constriction (narrowing) in the smallest blood vessels (capillaries) of the fingers in response to being exposed to cold as a stimulus. Patients with vasospastic symptoms as they are characteristic for Flammer syndrome have shown a unique gene expression when their lymphozytes underwent gene expression profiling.[7]