tokens: We discovered a missense mutation , GCA to GTA ( Ala 54 Val ) , in exon 2 in a neurofibrosarcoma patient ( case 1 ) , two missense mutations , AAA to CAA ( Lys 118 Gln ) and GAA to GGA ( Glu 154 Gly ) in exon 5 of another neurofibrosarcoma patient ( case 2 ) , and 3 amino acid substitutions , GTG to GCG ( Val 179 Ala ) , GTT to GCT ( Val 181 Ala ) and TTC to CTC ( Phe 186 Leu ) , in a third neurofibrosarcoma patient ( case 3 ) .