A DELETION IN THE 5'-REGION OF THE NEUROFIBROMATOSIS TYPE-1 (NF1) GENE

A new mutation, the first one close to the 5'-end of the neurofibromat osis type 1 (NF1) gene, was found when RNA preparations from various c ell types of 15 NF1 patients were analysed by reverse transcription an d subsequent multiplex polymerase chain reaction. This mutation remove s the 84 bp of exon 3 precisely from the cDNA. Genomic Southern blots revealed a larger deletion with breakpoints within the introns flankin g exon 3. This mutation suggests that the amino-terminal region of neu rofibromin is functionally significant. When using this mutation to di stinguish the wild type and mutant alleles, their expression could be analysed in neurofibroma fibroblasts, melanocytes from the unaffected skin, and those from a cafe-au-lait macule. In all these cell types, t he products of both alleles were detected, confirming similar results obtained with a different NF1 gene mutation.