PT - JOURNAL ARTICLE AU - John, Alison M AU - Ruggieri, Martino AU - Ferner, Ros AU - Upadhyaya, Meena TI - A search for evidence of somatic mutations in the<em>NF1</em> gene AID - 10.1136/jmg.37.1.44 DP - 2000 Jan 01 TA - Journal of Medical Genetics PG - 44--49 VI - 37 IP - 1 4099 - http://jmg.bmj.com/content/37/1/44.short 4100 - http://jmg.bmj.com/content/37/1/44.full SO - J Med Genet2000 Jan 01; 37 AB - Neurofibromatosis type I (NF1) is an autosomal dominant disorder affecting 1 in 3000 people. The NF1gene is located on chromosome 17q11.2, spans 350 kb of genomic DNA, and contains 60 exons. A major phenotypic feature of the disease is the widespread occurrence of benign dermal and plexiform neurofibromas. Genetic and biochemical data support the hypothesis thatNF1 acts as a tumour suppressor gene. Molecular analysis of a number of NF1 specific tumours has shown the inactivation of both NF1 alleles during tumourigenesis, in accordance with Knudson's “two hit” hypothesis. We have studied 82 tumours from 45 NF1 patients. Two separate strategies were used in this study to search for the somatic changes involved in the formation of NF1 tumours. First, evidence of loss of heterozygosity (LOH) of the NF1 gene region was investigated, and, second, a screen for the presence of sequence alterations was conducted on a large panel of DNA derived from matched blood/tumour pairs. In this study, the largest of its kind to date, we found that 12% of the tumours (10/82) exhibited LOH; previous studies have detected LOH in 3-36% of the neurofibromas examined. In addition, an SSCP/HA mutation screen identified five novelNF1 germline and two somatic mutations. In a plexiform neurofibroma from an NF1 patient, mutations in bothNF1 alleles have been characterised.