[39] High Frequency of Chromosome 11 Loss in Embryonal Rhabdomyosarcoma Detected by SNP Array Tumoral Genotyping

D Bouron-Dal Soglio, AL Rougemont, R Absi, S Barrette, R Fetni, A Montpetit, JC Fournet. Hospital Sainte-Justine, Montreal, QC, Canada; Genome Quebec, Montreal, QC, Canada

Background: Rhabdomyosarcoma (RMS) is the most frequent malignant pediatric soft tissue tumor. In pediatric population, RMS are divided into the more prevalent embryonal (ERMS) and the more aggressive alveolar rhabdomyosarcoma (ARMS), characterized by the presence of a translocation t(1;13)(p36;q14) or t(2;13)(q35;q14) in 80% of cases. In ERMS, no specific molecular abnormality has been yet described. However, 11p15.5 loss of heterozygosity (LOH) have been described in some ERMS, suggesting that a tumor suppressor gene in this region might be involved in the tumorigenesis of this model.
Design: We performed here the first whole-genome tumoral genotyping by high-definition SNP-array (Illumina Centrix 110 K) of a series of 11 pediatric RMS including 3 ARMS and 8 ERMS.
Results: A LOH at 11p15.5 has been observed in 7 out of 8 ERMS including 5 copy neutral LOH of the whole chromosome 11, a monosomy 11 and a copy neutral LOH limited to the 11p15.5 region. Numerical chromosomal abnormalities were also identified in ERMS, including trisomy 2, 7, 8 19 and 21. In contrast, a numerical chromosomal change was observed only in one ARMS. ARMS exhibited several different regional amplifications including amplification of the oncogenic fusion gene.
Conclusions: The high frequency of LOH at chromosome 11 or 11p15.5 in ERMS (7 out of 8) suggests us that they must be specific to ERMS comparing to ARMS and could be useful for the differential diagnosis of these two tumoral entities. They are underestimated in litterature, regarding the lack of identification of copy neutral LOH by CGH array techniques.
Category: Bone & Soft Tissue

Monday, March 9, 2009 1:00 PM

Poster Session II # 17, Monday Afternoon