Characterization of four mutations in the neurofibromatosis type 1 gene by denaturing gradient gel electrophoresis (DGGE).

Neurofibromatosis type 1 (NF1) is one of the most common inherited disorders. The gene responsible for the disease has a very high mutation rate, approximately fifty per cent of NF1 patients appear to have a de novo mutation. The search for mutations is hampered by the large size of the NF1 gene and up to date, relatively few mutations have been characterized. In the present work, we report the results of screening seventy unrelated NF1 patients for mutations in NF1 exons 29 and 31 by using an experimental approach that combines the polymerase chain reaction (PCR) with denaturing gradient gel electrophoresis (DGGE). Four mutations were identified and characterized. Three of them consist of C-T transitions resulting in nonsense mutations, two in exon 29, C5242T and C5260T, and one in exon 31, C5839T. The fourth mutation consists of a two-base pair deletion in exon 31, 5843delAA, also resulting in a premature stop codon. The finding in our patients of mutation C5839T, previously reported in three independent studies, supports that this position is a hotspot within the NF1 gene.