Follicular lymphoma in situ and partial involvement by follicular lymphoma are clona lesions that carry the t(14;18) and lack genetic secondary alterations

ABSTRACT: Follicular lymphoma (FL) is characterized by the t(14;18)(q32;q21), frequent numerical chromosomal alterations, and recurrent somatic mutations. However, no genetic studies are available for FL in situ (FLIS), a putative precursor lesion of FL. In this study, we analyzed cases of FLIS without manifest (m)FL, partial involvement by FL (PFL), and paired cases of FLIS and mFL to detect possible early chromosomal imbalances, as well as DNA-methylation patterns of genomic regions of selected genes. We demonstrated that paired FLIS and mFL cases are always clonally related. FLIS and PFL have no or few secondary chromosomal imbalances detectable by copy number arrays and a lower level of gene methylation as compared to mFL. Additionally, EZH2 Tyr641 mutations were detected in a subset of both FLIS and PFL cases. In conclusion, this study provides evidence that FLIS represents a FL precursor lesion of long-lived clonal B-cells carrying the t(14;18) with no or few secondary genetic changes. The earliest secondary genetic alterations detected in FLIS are the EZH2 Tyr641 mutation and low levels of CNAs, as evidence of clonal evolution. Our data suggest that there may be more than one distinct lesion driving the progression from FLIS to manifest lymphoma. DNA from cases, 20 tumor samples (10 in situ Follicular lymphoma, 4 Partial infiltration folliculary lymphoma and 6 manifest FL) were analyzed with Agilent-014693 Human Genome CGH Microarray 244A platform for copy number alterations study. For cases 9-14 paired samples of in situ follicular lymphoma and manifest follicular lymphoma were analyzed. Agilent-014693 Human Genome CGH Microarray 244A arrays were performed according to the manufacturer's directions on DNA extracted from lymph nodes that were hybridized against a normal DNA (pool) of the same gender.

ORGANISM(S): Homo sapiens

SUBMITTER: Itziar Salaverria 

PROVIDER: E-GEOD-48548 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress