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Analysis of the NF1 gene by temperature gradient gel electrophoresis reveals a high incidence of mutations in exon 4b
Author(s) -
Toliat Mohammed R.,
Erdogan Fikret,
Gewies Andreas,
Fahsold Raimund,
Buske Annegret,
Tinschert Sigrid,
Nürnberg Peter
Publication year - 2000
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/(sici)1522-2683(20000201)21:3<541::aid-elps541>3.0.co;2-l
Subject(s) - exon , microbiology and biotechnology , biology , genetics , genomic dna , gene , temperature gradient gel electrophoresis , polymerase chain reaction , missense mutation , intron , denaturing high performance liquid chromatography , mutation , 16s ribosomal rna
A total of 196 unrelated patients with neurofibromatosis type 1 (NF1) was screened for mutations in exons 4a‐c of the NF1 gene by temperature gradient gel electrophoresis (TGGE) of polymerase chain reaction (PCR)‐amplified genomic DNA fragments using intron‐based primers. DNA samples with abnormal TGGE band patterns were subjected to sequence analysis. Sequence alterations were identified in ten patients (5.1%): 496delGT (1), 499delTGTT (4), T528A=D176E (2), T539A=L180X (1), 540insA (1), C574T=R192X (1). Thus, a total of six different mutations was identified in exon 4b but none in exons 4a and 4c. Only the missense mutation D176E, which we assume to be a nonpathogenic polymorphism, and the 4‐base pair (bp) deletion 499delTGTT have been described before. The reason for the high incidence of mutations in exon 4b is obviously a tetranucleotide tandem repeat comprising nucleotides 495—502 (TGTTTGTT) that may give rise to slipped mispairing and subsequent deletion of one repeat unit during replication. Additionally, the recurrent 4 bp deletion was found as a second hit in a malignant schwannoma of a further NF1 patient, suggesting that microlesions may be as frequent among somatic as among germline mutations. This is the first report of a systematic study of NF1 exons 4a‐c in a large group of NF1 patients.