Expression of HERV-K, FGFR1, and the fusion genes.

(A) RT-PCR assay was performed on RNA extracted from leukemic cells containing the t(8;19)(p12;q13.3) and from healthy donor cells (control). HERV-K-FGFR1–specific transcript was detected in the patient sample but not in the healthy control sample.FGFR1 (2 variant products) and HERV-K (1 product) were detected in both patient and control samples. Chromosomal positions are indicated at the top. PCR products are indicated on the right and left. Primer sequences are given in “Study design.” Primer pairs used were as follows: row 1 (chr19), HERV-K–sense and –antisense; row 2 (der(19)), HERV-K–sense and FGFR1-antisense; row 3 (der(8)), FGFR1-sense and HERV-K–antisense; row 4 (chr8), FGFR1-sense and -antisense (the latter primer pair detected 2 variants of the wild-type FGFR1). (B) The Southern blot of the PCR products shown in panel A was probed with the oligonucleotide spanning the breakpoint, which is described in “Study design.” (C) Expression of the HERV-K gene. RT-PCR products were obtained from a variety of tissues (tissue type is indicated above each blot). Each panel is a photograph of the ethidium bromide–stained agarose gel in which PCR products were electrophoresed. β2-Microglobulin amplification was used to estimate the efficiency of RT-PCR reactions. PCR product sizes (bp) are indicated on the left.