[Analysis of c-kit and JAK2 gene mutations in t(8;21) acute myeloid leukemia]

To evaluate the prevalence of c-kit and JAK2 gene mutations in protein tyrosine kinase (PTK) family in adult t(8;21) acute myeloid leukemia (AML) and their implications.

Genomic DNAs from 78 t(8;21) AML patients were screened for mutated c-kit (mutKIT) in exon 8 and 17 by PCR and sequencing. JAK2 V617F mutation screening was processed by allele-specific PCR.

(1) Among 78 t(8;21) AML patients, 27 (34.6%) had muc-kit/JAK2 and 6 (7.7%) had JAK2 V617F, and none had both. (2) Peripheral WBC count was higher in mutKIT/JAK2 V617F patients than in wide-type c-kit/JAK2 (wtKIT/JAK2) patients \[(36.2 +/- 37.7) x 10(9)/L vs (21.7 +/- 21.1) x 10(9)/L\] (P < 0.05). There was no significant difference in hemoglobin level, platelet counts, percentage of blast cell in bone marrow, CD117 expression level, the age of onset and gender between the two groups. Peripheral WBC count was higher in mutKIT patients \[(38.8 +/- 40.7) x 10(9)/L\] than in wtKIT patients \[(22.0 +/- 20.4) x 10(9)/L\] (P < 0.05). (3) Complete remission (CR) rates between patients with mutkit/JAK2 V617F and with wtKIT/JAK2 were similar (69.6% vs 80.0%, P > 0.05), but the 2 year continuous CR (CCR) rate was lower in patients with mutKIT/JAK2 V617F (26.7% vs 56.1%, P < 0.05). However, there was no significant difference in OS between mutKIT/JAK2 V617F and wtKIT/JAK2 patients (34.8% vs 58.6%, P > 0.05).

Occurrence of c-kit and JAK2 gene mutations especially c-kit mutation is common in t(8;21) AML patients, and is associated with higher WBC. These mutations confer higher relapse risk and predict poor prognosis.