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PURPOSE: The specific aims of the AIEOP-TW-2003 protocol included prospectively investigating a possible association of tumor loss of heterozygosity with outcomes in children treated for Wilms tumor. MATERIALS AND METHODS: We analyzed 125 unilateral favorable histology Wilms tumors registered between 2003 and 2008 in the Italian cooperative protocol for microsatellite markers mapped to chromosomes 1p, 7p, 11q, 16q and 22q. RESULTS: The 3-year disease-free survival and overall survival probabilities were 0.87 (95% CI 0.81-0.93) and 0.98 (95% CI 0.96-1.0), respectively. Loss of heterozygosity at 1p was significantly associated with a worse disease-free survival (probability 0.67 for patients with and 0.92 for those without 1p loss of heterozygosity, p = 0.0009), as confirmed also by multivariate analysis adjusting for tumor stage and patient age at diagnosis. There was no difference in disease-free survival probability among children with loss of heterozygosity in the other chromosomal regions tested. The worse outlook for children older than 2 years at diagnosis did not seem to be influenced by the loss of heterozygosity patterns considered. CONCLUSIONS: Chromosome 1p loss of heterozygosity seems to be a risk factor for nonanaplastic Wilms tumor, possibly regardless of other clinical factors. Our findings were uninformative regarding loss of heterozygosity in the other chromosomal regions tested.

Multiple primary malignant neoplasms are rare entities in the clinical setting, but represent an important issue in the clinical management of patients since they could be expression of a genetic predisposition to malignancy. A high resolution genome wide array CGH led us to identify the first case of a de novo constitutional deletion confined to the FBXW7 gene, a well known tumor suppressor, in a patient with a syndromic phenotype characterized by focal segmental glomerulosclerosis and multiple primary early/atypical onset tumors, including Hodgkin’s lymphoma, Wilms tumor and breast cancer. Other genetic defects may be associated with patient’s phenotype. In this light, constitutional mutations at BRCA1, BRCA2, TP53, PALB2 and WT1 genes were excluded by performing sequencing and MLPA analysis; similarly, we ruled out constitutional abnormalities at the imprinted 11p15 region by methylation specific -MLPA assay. Our observations sustain the role of FBXW7 as cancer predisposition gene and expand the spectrum of its possible associated diseases.

Despite the excellent survival rate of Wilms tumor (WT) patients, only approximately one-half of children who suffer tumor recurrence reach second durable remission. This underlines the need for novel markers to optimize initial treatment. We investigated 77 tumors using Illumina 370CNV-QUAD genotyping BeadChip arrays and compared their genomic profiles to detect copy number (CN) abnormalities and allelic ratio anomalies associated with the following clinicopathological variables: relapse (yes vs. no), age at diagnosis (≤24 months vs. >24 months), and disease stage (low stage, I and II, vs. high stage, III and IV). We found that CN gains at chromosome region 1q21.1-q31.3 were significantly associated with relapse. Additional genetic events, including allelic imbalances at chromosome arms 1p, 1q, 3p, 3q, and 14q were also found to occur at higher frequency in relapsing tumors. Interestingly, allelic imbalances at 1p and 14q also showed a borderline association with higher tumor stages. No genetic events were found to be associated with age at diagnosis. This is the first genome wide analysis with single nucleotide polymorphism (SNP) arrays specifically investigating the role of genetic anomalies in predicting WT relapse on cases prospectively enrolled in the same clinical trial. Our study, besides confirming the role of 1q gains, identified a number of additional candidate genetic markers, warranting further molecular investigations. © 2012 Wiley Periodicals, Inc.

For many years the precise genetic etiology of the majority of Wilms' tumors has remained unexplained. Recently, the WTX gene, mapped to chromosome Xq11.1, has been reported to be lost or mutated in approximately one-third of Wilms' tumors. Moreover, in female cases, the somatically inactivated alleles were found to invariantly derive from the active chromosome X. Consequently, WTX has been proposed as a 'one-hit' tumor suppressor gene. To provide further insights on the contribution of WTX to the development of the disease, we have examined 102 Wilms' tumors, obtained from 43 male and 57 female patients. Quantitative PCR analyses detected WTX deletions in 5 of 45 (11%) tumors from males, whereas loss of heterozygosity at WTX-linked microsatellites was observed in 9 tumors from 50 informative females (19%). However, in the latter group, using a combination of HUMARA assay and bisulfite-modified DNA sequencing, we found that the deletion affected the active chromosome X only in two cases (4%). Sequence analyses detected an inactivating somatic mutation of WTX in a single tumor, in which a strongly reduced expression of the mutant allele respect to the wild-type allele was observed, a finding not consistent with its localization on the active chromosome X. Overall, a functional somatic nullizygosity of the WTX gene was ascertained only in seven of the Wilms' tumors included in the study (approximately 7%). Our findings indicate that previously reported estimates on the proportion of Wilms' tumors due to WTX alterations should be reconsidered.

The parent of origin-dependent expression of the IGF2 and H19 genes is controlled by the imprinting centre 1 (IC1) consisting in a methylation-sensitive chromatin insulator. Deletions removing part of IC1 have been found in patients affected by the overgrowth- and tumour-associated Beckwith - Wiedemann syndrome (BWS). These mutations result in the hypermethylation of the remaining IC1 region, loss of IGF2/H19 imprinting and fully penetrant BWS phenotype when maternally transmitted. We now report that 12 additional cases with IC1 hypermethylation have a similar clinical phenotype but showed neither a detectable deletion nor other mutation in the local vicinity. Likewise, no IC1 deletion was detected in 40 sporadic non-syndromic Wilms' tumours. A detailed analysis of the BWS patients showed that the hypermethylation variably affected the IC1 region and was generally mosaic. We observed that all these cases were sporadic and in at least two families affected and unaffected members shared the same maternal IC1 allele but not the abnormal maternal chromosome epigenotype. Furthermore, the chromosome with the imprinting defect derived from either the maternal grandfather or maternal grandmother. Overall, these results indicate that methylation-imprinting defects at the IGF2-H19 locus can result from inherited mutations of the IC and have high recurrence risk or arise independently from the sequence context and generally not transmitted to the progeny. Despite these differences, the epigenetic abnormalities are usually present in the patients in the mosaic form and probably acquired by post-zygotic de novo methylation. Distinguishing between these two groups of cases is important for genetic counselling. © The Author 2008. Published by Oxford University Press. All rights reserved.

Background We evaluated an intensified chemotherapy strategy in children with Wilms tumor who relapsed with high-risk features. Procedures From January 2001 to June 2006, we treated 20 consecutive children with reinduction chemotherapy (using ifosfamide/carboplatin/etoposide in 15/20 cases), with (n = 15) or without (n = 5) subsequent high-dose chemotherapy and hematopoietic stem cell support, surgery where feasible, and radiation therapy. The median time to relapse was 10 months after nephrectomy. All but two children initially received doxorubicin as first-line therapy. Results All patients were assessed for outcome: 13 are currently alive, 12 of them in remission a median 25 months since their relapse, one with progressing tumor. The treatment was unsuccessful in eight children: the disease progressed during reinduction in three, and relapsed in five. There was one toxic death. All transplanted patients engrafted to a neutrophil count >0.5 × 103/µl after a median 11 days, and to an unsustained platelet count >25,000/µl after a median of 13 days. Three-year disease-free and overall survival rates were 56 ± 12% and 55 ± 13%, respectively. Neither recurrence within 12 months of nephrectomy nor extra-lung recurrence negatively affected outcome. A survival advantage was demonstrated in patients without disease evidence prior to transplant. Conclusion A disease-free survival rate nearing 50% is a realistic target in children with high-risk recurrent Wilms tumor. The benefit of autologous hematopoietic stem cell transplantation for consolidation deserves to be investigated in a randomized, controlled study. Pediatr Blood Cancer 2008;51:23–28. © 2008 Wiley-Liss, Inc.