Artikel
Microdeletions and gains of 1p36 and 22qter in meningiomas detected by inter- and metaphase FISH enlarge predictive value of these markers
Mittels Inter- und Metaphase-FISH nachgewiesene Mikrodeletionen und Gewinne auf 1p36 und 22qter erweitern die prognostische Bedeutung dieser Marker
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Veröffentlicht: | 8. Mai 2006 |
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Objective: The majority of meningiomas show either monosomy of chromosome 22 or a diploid karyotype. Deletion of the short arm of chromosome 1 is known as the most important marker associated with progression, but there are also many progressive meningiomas without deletion of 1p. The aim of our study was to investigate possible small deletions of the chromosomal regions 1p36 and 22qter by FISH, which are not detectable by conventional G-banding and to correlate the results with conventional karyotyping, histo pathological and clinical parameters.
Methods: According to our hypothesis of terminal deletions on chromosome 22 we used two color FISH with a telomerspecific probe for the chromosome region 22 (22qter) in combination with a probe for the chromosomal region 1p36. The alkaline phosphatase (ALPL) is located in the latter region, which is considered to be a tumorsuppressor gene. These probes were also used to reveal what, until now, were unknown correlations of these most frequent aberrations. With metaphase FISH we were able to investigate structural rearrangements of these chromosomal regions.
Results: We found 5/35 cases with deletions of 22qter, that were not detectable by standard karyotyping. 3 of those 5 cases were WHO grade III meningiomas, one a grade II and one recurrence. We found signal-duplication at the 22qter region, extra-chromosomal 22qter signals, as well as translocations of 22qter to other chromosomes by metaphase-FISH. In 7/35 cases we found deletions of 1p36(4 grade III, 1 grade II and 2 recurrences).
Conclusions: We found gains in the 22qter region and assume that the cell tries to compensate this imbalance by excluding parts of chromosome 22. This may lead to deletion or even monosomy 22 on the one hand, and extra-chromosomal and translocated 22q regions on the other hand. Based on these data, FISH with 22qter and 1p36 can show additional predictive values for patients suffering from meningiomas with non-detectable 22q and/or 1p36 deletions in G-banding.