Identification of TET2 loss-of-function phenotype by LC-ESI-MS/MS-MRM in the normal aging population

Abstract

doi:10.1016/j.exphem.2014.07.090 Get rights and content The incidence of myeloid malignancies such as acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) increases dramatically with age, yet tools to identify individuals at risk are lacking. Using a well characterized cohort of normal aging individuals prospectively established between 1998 and 2006, we previously showed that mutations in the TET2 gene occur in the normal aging population (in ≈4% of individuals >65, n=444). We hypothesized that these events could be pre-leukemic and involved in the initiation of age-associated myeloid cancers. The TET2 gene encodes a methylcytosine dioxygenase responsible for the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), consequently TET2 loss-of-function results in low global 5hmC levels. Here we show that in addition to the prevalence of TET2 mutations, increased age is characterized by a continuous and significant reduction in global 5hmC levels in total blood cells as shown by LC-ESI-MS/MS-MRM (29% from birth to old age, n=197, p<0.05). Using this newly developed and validated ultra-sensitive method, we were also able to document a linear correlation between 5hmC levels and TET2 variant allele frequencies (VAF) as determined by next-generation sequencing (n=378). When defining a significant