VHL expression in lymphoblastoid cells from a control subject (Con), 2 heterozygotes (P24 and P25), and a homozygote (P22). (A) Total RNA from each cell line was retrotranscribed to cDNA, which was amplified as reported in “Patients, materials, and methods,” and the product (377 bp) was digested with FnU4HI. The normal allele yielded 2 fragments of 245 bp and 132 bp. The C598T mutation abolished the restriction site and resulted in an uncut 377-bp band. The 2 heterozygote patients (P24 and P25) expressed the allele in roughly similar amounts. Conversely, the homozygote for the VHL mutation shows a single undigested band. (B) The expression of the actin gene served as control.