Isochromosome 17q demonstrated by interphase fluorescence in situ hybridization in primitive neuroectodermal tumors of the central nervous system

Abstract

We previously reported an i(17q) as a non-random finding in childhood primitive neuroectodermal tumors (PNETs) of the central nervous system. In the present study, we describe a two-color interphase fluorescence in situ hybridization (FISH) assay for detection of chromosome 17 abnormalities in tumors. Thirty-four PNETs were analyzed by FISH with a series of chromosome 17-specific probes which map to 17p13.3-17q25. The results from the FISH assay were then compared to the karyotypes prepared from the tumors. Ten of the 34 cases demonstrated an i(17q) by FISH and standard cytogenetics. Two PNETs were shown to have an i(17q) by FISH alone, and three additional tumors had deletions of 17p. Thus, a total of 15 of 34 (44%) of the PNETs in this series had a deletion of 17p. This study confirms and extends our previous reports that an i(17q) is the most common cytogenetic abnormality in PNETs. The interphase FISH assay which we employed will have clinical utility for diagnosis of children with malignant brain tumors, and it may be used for identification of tumors with 17p deletions for molecular studies aimed at identifying disease genes.

Comparative genomic hybridization and histological variation in primitive neuroectodermal tumours

“…Furthermore, the mutual exclusivity we demonstrated between tumours exhibiting gain of 17q and those showing immunoreactivity for GFAP has also not been described previously. This result contrasts with the results of one study in which the majority of PNETs with i(17q) showed 'glial differentiation' (Biegel et al, 1995). The GFAP gene is located at 17q21, but it is unclear how gain of 17q might interfere with the expression of this astroglial intermediate filament (Brenner et al, 1994).…”

Comparative genomic hybridization detects many recurrent imbalances in central nervous system primitive neuroectodermal tumours in children

“…The most frequent abnormality is isochromosome i(17q), found in approximately 30% of cases analysed with conventional cytogenetics (Bigner et al, 1988;Griffin et al, 1988;Biegel et al, 1989;Karnes et al, 1992;VagnerCapodano et al, 1992;Neumann et al, 1993;Fujii et al, 1994). This high incidence of i(17q) was confirmed in a molecular cytogenetic study, which also showed deletions of 17p in 44% of patients (Biegel et al, 1995). Other studies using molecular approaches confirmed this frequent loss of 17p, and localized a hot-spot of loss of heterozygosity at 17p13.3, a locus telomeric to the p53 gene (Biegel et al, 1992;Cogen et al, 1992;McDonald et al, 1994;Batra et al, 1995).…”

Isochromosomes in acute lymphoblastic leukaemia: I(21q) is a significant finding

“…FISH has been used to show that i(l7q) was present in cases of medulloblastoma where it was not detected by cytogenetics (Vagner-Capodano et al, 1994;Biegel et al, 1995), whereas, in haematological malignancies, the same technique revealed more i( 17q) cells in some cases than did cytogenetics (Shi et al, 1994).…”