Constitutional von Hippel-Lindau (VHL) gene deletions detected in VHL families by fluorescence in situ hybridization.

von Hippel-Lindau (VHL) disease is an autosomal dominantly inherited cancer syndrome predisposing to a variety of tumor types that include retinal hemangioblastomas, hemangioblastomas of the central nervous system, renal cell carcinomas, pancreatic cysts and tumors, pheochromocytomas, endolymphatic sac tumors, and epididymal cystadenomas [W. M. Linehan et al., J. Am. Med. Assoc., 273: 564-570, 1995; E. A. Maher and W. G. Kaelin, Jr., Medicine (Baltimore), 76: 381-391, 1997; W. M. Linehan and R. D. Klausner, In: B. Vogelstein and K. Kinzler (eds.), The Genetic Basis of Human Cancer, pp. 455-473, McGraw-Hill, 1998]. The VHL gene was localized to chromosome 3p25-26 and cloned [F. Latif et al., Science (Washington DC), 260: 1317-1320, 1993]. Germline mutations in the VHL gene have been detected in the majority of VHL kindreds. The reported frequency of detection of VHL germline mutations has varied from 39 to 80% (J. M. Whaley et al., Am. J. Hum. Genet., 55: 1092-1102, 1994; Clinical Research Group for Japan, Hum. Mol. Genet., 4: 2233-2237, 1995; F. Chen et al., Hum. Mutat., 5: 66-75, 1995; E. R. Maher et al., J. Med. Genet., 33: 328-332, 1996; B. Zbar, Cancer Surv., 25: 219-232, 1995). Recently a quantitative Southern blotting procedure was found to improve this frequency (C. Stolle et al., Hum. Mutat., 12: 417-423, 1998). In the present study, we report the use of fluorescence in situ hybridization (FISH) as a method to detect and characterize VHL germline deletions. We reexamined a group of VHL patients shown previously by single-strand conformation and sequencing analysis not to harbor point mutations in the VHL locus. We found constitutional deletions in 29 of 30 VHL patients in this group using cosmid and P1 probes that cover the VHL locus. We then tested six phenotypically normal offspring from four of these VHL families: two were found to carry the deletion and the other four were deletion-free. In addition, germline mosaicism of the VHL gene was identified in one family. In sum, FISH was found to be a simple and reliable method to detect VHL germline deletions and practically useful in cases where other methods of screening have failed to detect a VHL gene abnormality.

Molecular cytogenetic fingerprinting of esophageal squamous cell carcinoma by comparative genomic hybridization reveals a consistent pattern of chromosomal alterations.

Esophageal cancer is the third most prevalent gastrointestinal malignancy in the world. The tumor responds poorly to various therapeutic regimens and the genetic events underlying esophageal carcinogenesis are not well understood. To identify overall chromosomal aberrations in esophageal squamous cell carcinoma, we performed comparative genomic hybridization (CGH). All 17 tumor samples were found to exhibit multiple gains and losses involving different chromosomal regions. The frequency of chromosomal loss associated with this type of tumor was as follows: in 2q (100%), 3p (100%), 13q (100%), Xq (94%), 4 (82%), 5q (82%), 18q (76%), 9p (76%), 6q (70%), 12q (70%), 14q (65%), 11q (59%), and 1p (53%). Interstitial deletions on 1p, 3p, 5q, 6q, 11q, and 12q were detected also. Chromosomal gains were displayed by chromosomes and chromosome areas: 19 (100%), 20q (94%), 22 (94%), 16p (65%), 17 (59%), 12q (59%), 8q (53%), 9q (53%), and 3q (50%). Two sites showing apparent amplification were 11q (70%) and 5p15 (47%). To validate the CGH data, we isolated a BAC clone mapping to 18q12.1. This clone was used as a probe in interphase fluorescence in situ hybridization of tumor touch preparations and allelic loss was clearly revealed. This study represents the first whole-genome analysis in esophageal squamous cell carcinoma for associated chromosomal aberrations that may be involved in either the genesis or progression of this malignancy.