LOH 4q24 mapping and TET2 sequencing. (A) Topographical map illustrating overlapping regions of UPD4q24 (purple bars) and del4q24 (orange bars) in patients with myeloid malignancies. A minimally affected region on 4q24 (0.35 Mb), containing TET2 and PPA2, was identified in 18 of 398 patients studied (* indicates that some patients' DNA was not available for mutational screening; n = 3). (B) Representative examples of SNP-A karyograms (CNAG version 3.0) of chromosome 4 of both whole bone marrow cells and paired CD3⁺ lymphocytes in 2 patients, demonstrating the somatic nature of acquired LOH4q24 and TET2 mutations, which are shown in corresponding ferrograms in the right portion of the figure. SNP-A karyograms: rows a and b correspond to the copy number as measured by the intensity of individual hybridization signals; row c represents frequency of heterozygous calls; and row d indicates the allelic imbalance with parental allele copy numbers.