Fluorescent in situ hybridization (FISH) reveals frequent and recurrent numerical and structural abnormalities in hepatoblastoma with no informative karyotype

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Abstract
Background Hepatoblastoma (HB) is the most frequent malignant liver tumor in children. The few cytogenetic studies available indicate that HB is associated with recurring trisomies of chromosomes 2, 8, and 20; recurrent t(1;4) (q12;q34) has been reported in few cases. The abnormalities of chromosome 1q are relatively frequent and usually lead to overexpression of 1q material. A cluster of breakpoints is located at the level of bands 1q12 and 1q21. More work is needed to clarify their real incidence and prognostic significance. Cytogenetic analysis is limited by the requirement of suitable cells in metaphase. A different method that increases analysis sensitivity is fluorescent in situ hybridization (FISH). Procedure We studied 10 cases of HB with no informative karyotype (normal karyotype or no metaphases). FISH was performed by the standard method, using cytospins and imprints obtained from frozen or cytogenetic samples of direct cultures. Alpha‐satellite probes for centromeric DNA were used for chromosomes 2, 8, and 20 analysis; rearrangement of region 1q12‐21 was detected with BAC (bacterial artificial chromosome) probe bA79E5. Results We detected at least one trisomic clone in 5/10 of these cases. Trisomy 20 was the most frequently detected abnormality, followed by trisomy of the chromosomes 2 and 8. Analysis of 1q12 band revealed that the rearrangement of 1q usually is in pericentromeric heterochromatin, it was present in 5/10 of studied cases. Conclusion FISH analysis is recommended in all cases of HB with no informative karyotype to gain more information regarding the frequent trisomies encountered and their significance. Med Pediatr Oncol 2002;39:536–539.