CYP2C19 and transient ischemic attack: There was no significant difference for occurrence of severe or moderate bleeding between the groups.67 It should be pointed out that one limitation was that in the study the included patients were not compared to non-carriers of the CYP2C19 loss-of-function alleles.67 The National Institute for Health and Care Excellence (NICE) guidelines now suggests CYP2C19 genotype testing to assess if clopidogrel is a suitable antiplatelet drug for people who have just had an ischemic stroke or a transient ischemic attack (TIA) (www.nice.org.uk/guidance/dg59).