Unusual chromosome patterns of renal cell carcinomas common to two brothers

Familial papillary renal carcinoma: cytogenetic characterization in normal and tumor tissues in two brothers. A case report

BACKGROUND

Renal tumor subtypes are associated with distinct, recurring cytogenetic abnormalities and hereditary cancer syndromes. In papillary renal carcinoma, trisomy 7 and 17 and loss of the Y chromosome are the most common chromosomal defects.

CASE PRESENTATION

The present paper analyzes the chromosomes 7, 17, and Y alterations found in familial papillary carcinoma and in the normal tissue of two brothers. The evaluation, performed by fluorescence in situ hybridization (FISH) and cytogenetic conventional methods, was carried out on blood samples, normal kidney tissue, and tumor samples of the two brothers. Patient 1 showed gains of chromosomes 7 and 17 both in normal and tumor tissue. Chromosome Y status was normal. Patient 2 showed chromosome 7 and 17 gains, chromosome Y loss in tumor and chromosome 17 and Y alterations in normal kidney tissue. The constitutional karyotype was normal in both brothers.

CONCLUSIONS

Of particular relevance were the chromosome aberrations found in normal kidney parenchyma. In fact, the progressive alterations of 7, 17, and Y chromosomes could provide evidence of early genetic instability of tissue and may even precede the development of macroscopically identifiable lesions.

Common pattern of unusual chromosome abnormalities in hereditary papillary renal carcinoma

In this study, we summarized cytogenetic and comparative genomic hybridization (CGH) results, mutation analysis of the MET gene, and immunohistochemistry results of tumors from three patients in the same family who were affected by hereditary papillary renal carcinoma (HPRC). All three patients showed germline mutations in the tyrosine kinase domain of the MET proto-oncogene, and developed bilateral and multiple papillary renal tumors. DNA mutation analysis showed an increased dosage of the mutant allele in six tumors from two patients but not in two tumors from the third patient. In addition to the recurrent chromosomal alterations found in papillary renal carcinomas, cytogenetic analyses revealed the presence of an identical chromosomal translocation, t(2;15)(q13;p11), in two different tumors from the same patient. Moreover, the same pattern of autosomal trisomies (+7, +12, +13, +17) was detected by CGH analysis in tumors from different siblings. Taking into account that the presence of an identical structural chromosomal aberration in two tumors and the gain of chromosome 13 are unusual chromosomal changes in this type of tumor, we can conclude that our results confirm those of other authors and suggest that the genetic predisposition to HPRC might predispose the acquisition of genomic alterations in specific chromosomes or chromosomal regions.