Low expression of TET2 gene in pediatric acute lymphoblastic leukemia is associated with poor clinical outcome

TET2, a member of the Ten-Eleven translocation gene family, catalyzes the conversion of 5-methylcytosine to 5-hydroxymethylcytosine in DNA. Low expression of TET2 has been reported as a prognostic factor for several types of malignancies in adult patients. However, there have been few data on the effect of TET2 mRNA level on the prognosis of children with ALL so far.

In this study, TET2 expression of samples cryopreserved in the liquid nitrogen from January 1, 2007 through December 31, 2011 was retrospectively analyzed in 136 newly diagnosed ALL patients by real-time polymerase chain reaction (PCR) assay. The patients' samples were divided into two groups by the median value of patients group and divided into TET2 low and TET2 high groups.

A total of 136 childhood ALL patients demonstrated lower TET2 expression than control group (P = .038). TET2 mRNA expression levels were correlated with the disease status. In addition, patients with low TET2 expression had lower platelet counts and lower CR rates. Survival analysis showed that low TET2 expression in children with ALL was associated with lower 5-year overall survival (OS) (63% vs 88%, P = .011) and event-free survival (EFS) (60% vs 85%, P = .003). Multivariate analysis revealed that low TET2 expression was an independent poor prognostic factor of OS and EFS.

Low expression of TET2 in children with ALL is associated with poor prognosis and can be used as a molecular prognostic marker for risk group stratification.