Interestingly, except for one patient with SM-CEL, CR was restricted to WDSM patients showing mutations in exon 9 (K509I) of KIT, whereas all non-responder cases had wild-type KIT. To date, 7 adult SM patients showing mutations at exons other than exon 17 of KIT (exons 9 and 10) have been reported to be treated with imatinib. The gene discussed is KIT; the disease is systemic mastocytosis.