Detection of a novel germline mutation in the von Hippel-Lindau tumour-suppressor gene by fluorescence-labelled base excision sequence scanning (F-BESS)

The von Hippel-Lindau (VHL) syndrome is an inherited multi-tumour disorder characterised by clinical heterogeneity and high penetrance. The VHL gene has been shown to be a tumour-suppressor gene. A carrier of a germline mutation will be predisposed to a high variety of benign and malign tumours affecting different organ systems. As treatment of VHL malformations in presymptomatic stages will improve significantly the clinical outcome and the patient's quality of life, early and unambiguous detection of a germline mutation is mandatory. Direct sequencing especially of large genes might be laborious and time consuming. Therefore, most laboratories apply single strand conformational polymorphism (SSCP) analysis as an initial screening technique. Major disadvantages of this approach are the requirement of specialised equipment and a limited detection rate of about 70%. To overcome these problems, we applied the modified technique of fluorescence-labelled base excision sequence scanning (F-BESS). A young patient without family history of VHL with two hemangioblastoma of the cerebellum, pancreatic cysts and angiomatosis retinae was presented. Applying F-BESS, we detected a frameshift in exon 2 as a de novo germline mutation. Direct sequencing revealed an insertion of C at position 631/632. This is a novel VHL mutation, which results in truncation of the VHL protein omitting the Elongin-binding domain. Applying SSCP on the same DNA, no alteration could be detected. Three further family members were tested negative for the mutation by F-BESS in accordance with lack of any clinical VHL features. As F-BESS appears to be a reliable, fast and unexpensive method, we recommend this technique as an initial screening method.