Fragile site expression in families with von Hippel-Lindau disease.

Von Hippel-Lindau (VHL) disease is an autosomal dominant disorder that predisposes to diverse tumors including renal cell carcinoma. Six affected and four unaffected subjects from five families were studied to determine the frequency of fragile site expression. Peripheral lymphocyte cultures from each subject were treated with low folate, 5-fluorodeoxyuridine (FUdR), and FUdR plus caffeine for fragile site induction. A site was considered to be fragile if it was expressed at least two times in half of the affected or unaffected subjects. Of the established sites, four were expressed in the unaffected group (3p14, 6p22, 8q22, and Xp22) and six were expressed in the affected group (3p14, 4q31, 5q31, 7q32, Xp22, and Xq22). Only 3p14 and Xp22 were expressed in both groups. There were four new sites: three (3q26, 6p21, 7p15) in the unaffected group and one (16q24) in the affected group. The 3p14 site was expressed twice as frequently in affected versus unaffected subjects. This finding is of interest because of reports of the involvement of 3p14 in hereditary renal cell carcinoma and in VHL.