Absence of exon 17 c.2970-2872delAAT mutation in Turkish NF1 patients with mild phenotype.

INTRODUCTION: Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder characterized by café-au-lait spots, neurofibromas, skinfold freckles, Lisch nodules, bone deformities, learning disabilities, and predisposition to neoplasms. It is caused by various mutations of the NF1 gene. Recently a 3-bp in-frame deletion in exon 17, c.2970-2972 delAAT mutation, has been associated with a milder phenotype of NF1 manifesting with pigmentary skin changes only.

MATERIALS AND METHODS: We therefore analyzed 35 NF1 patients without neurofibromas, learning problems, or bone lesions (19 familial, 16 sporadic, age 7-44 years) for exon 17 mutations by DNA sequencing.

RESULTS: We did not find the c.2970-2972 delAAT mutation in this group but identified two base changes in exon 17 (c.2989A>G and c.2894T>A), whether these two novel mutations are related to a mild phenotype remains to be confirmed in further studies. Our results suggest the reported phenotypic associations may not be valid for all populations.