SFRP4 and acute myeloid leukemia: However, the frequencies of aberrant methylation of SFRP1, SFRP2, SFRP4, and SFRP5 (31.6%, 19.3%, 1.5%, and 12.6%, respectively; total 40.1%) in this study were lower than those (41%, 31%, 4%, and 22%, respectively) reported by Valencia et al (2009) who analysed 184 non-M3 AML patients, but were similar to those reported by Jost et al (2008).