Somatic mutation of the VHL gene in MEN2-associated MTC. Portion of the sequence of exon 1 from case 1 demonstrating a deletion of a single base (del C) at nucleotide 389 of the VHL gene in one allele at the position indicated by the arrow. This mutation would result in a shift in the translational frame of the encoded mRNA from codon 59 to a premature stop codon at position 66. Exons 1–3 of the VHL gene were amplified from genomic DNA using polymerase chain reaction conditions described elsewhere (Stolle et al.,1998). Mutation scanning by conformation sensitive gel electrophoresis (CSGE) was performed on the PCR products obtained using PCR conditions described by Ganguly et al., 1993. DNA sequence analysis was performed using a cycle sequencing kit with dye-labeled terminators (PE Advanced Biosystems, Inc., Foster City, CA). Sequences were analyzed on an ABI 377 automated DNA sequencer.