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D.J. Wallace, D. Shen, R.R. Buggage, R.B. Nussenblatt, C.C. Chan; Detection of bcl–2/IgH Gene Translocations in Primary Intraocular Lymphoma . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1071.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Primary intraocular lymphoma (PIOL) is a diffuse large B cell lymphoma (DLBCL) in which malignant lymphoid cells invade the retina, vitreous, or optic nerve head, with or without concomitant central nervous system involvement. The bcl–2 t(14;18) translocation brings the bcl–2 gene, an anti–apoptosis gene found on chromosome 18, under the control of the IgH promoter, located on chromosome 14, leading to Bcl–2 expression. This translocation is found in 85% of follicular non–Hodgkin’s lymphomas (FL) and 28% of diffuse large B–cell lymphomas (DLBCL). Sixty percent of Bcl–2 breakpoints are located at the major breakpoint region (Mbr) in the 3’ non–coding part of the third exon. The next most frequent location for translocations (10–25%) is the minor cluster region (mcr) located 20 kb downstream of the gene. The purpose of this study was to examine the distribution of these bcl–2 breakpoints in PIOL. Methods:Polymerase chain reaction (PCR) was performed on DNA extracted from microdissected PIOL cells. The Mbr was analyzed in 69 patients, and the mcr was analyzed in 67 patients. The PCR–amplifiable mixture contained microdissected DNA, 4 pmol 32P–labeled sense primer of Mbr, 5’–TTA GAG AGT TGC TTT ACG TGG CCT–3’ or mcr, 5’–GAC TCC TTT ACG TGC TGG TAC C–3’, 5 pmol antisense primer (CFW1), 5’–ACC TGA GGA GAC GGT GAC CAG GGT–3’, 10 nmol dNTP, 5 nmol MgCl2, and 0.5 U AmpliTaq Gold Enzyme in a final volume of 10 µL. The PCR reaction for the Mbr was performed as follows: 94°C for 9 min, then 40 cycles of 94°C x 45 sec, 55°C x 45 sec, and 72°C x 1 min, followed by 72°C for 7 min. The PCR reaction for the mcr was performed as follows: 94°C for 9 min, then 35 cycles of 94°C x 1 min, 55°C x 2 min, and 72°C x 2 min, followed by 72°C for 7 min. The amplified DNA was separated on a 3% agarose gel. The gel was then stained with ethidium bromide and autoradiographed. Results:37/69 (54%) PIOL patients expressed the t(14;18) translocation at the Mbr. 15/67 (22%) expressed the translocation at the mcr. Of these patients, 14/15 (93%) were also positive for the Mbr, indicating some overlap of the breakpoint regions, while 1/15 (7%) was positive only at the mcr. Conclusion: These results are similar to those seen in FL and DLBCL, indicating that this translocation may also play a role in PIOL pathogenesis. Furthermore, this translocation is used as a marker for diagnosis and monitoring of FL, although its role in prognosis and treatment selection for FL and DLBCL remains unclear. This study lays a foundation for future studies aimed at exploring the role of Bcl–2 expression in clinical presentation, treatment response, relapse, and survival in patients with PIOL.
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