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Abstract
Background:
Neurofibromatosis type 2 (NF2) is an autosomal dominant syndrome caused by the NF2 tumor suppressor gene. However, the NF2 mutation characteristics in Korean patients are not sufficiently understood. In this study, we conducted a comprehensive mutational analysis in 7 Korean NF2 patients by performing direct sequencing and gene-dosage assessment.
Methods:
We analyzed all exons and flanking regions of NF2 by direct sequencing and screened the deletions or duplications involving NF2 by multiplex ligation-dependent probe amplification.
Results:
Four novel NF2 mutations, including 2 splice-site mutations (c.364-1G>A and c.886-3C>G), 1 frameshift mutation (c.524delA), and 1 missense mutation (c.397T>C; p.Cys133Arg), were identified in our patients. No large deletion or duplication was identified in our series. Subsequently, we identified an abnormal splicing product by using reverse transcription-PCR and direct sequencing in 2 patients with a novel splice-site mutation. The missense mutation c.397T>C was predicted to have harmful effects on protein function.
REFERENCES
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Fig. 1.
Results of RT-PCR and sequence analysis for the 2 splice-site mutations c.364-1G>A (patient P4) and c.886-3C>G (patient P2). (A) The c.364-1G>A mutation yields a 0.55-kb abnormal product as well as 0.63-kb normal product in RT-PCR with the following primers: F-5′-AAGCAACCCAAGACGTTCAC-3′, R-5′-CCGGATTGCAAAGTAGTTCA-3′. (B) The c.886-3C>G cannot be discriminated from normal products by using following primers: F-5′-CTGACCCCCAAGATCTCCT-3′, R-5′-GCTTCAGCTGATCTGCCTCT-3′. (C) Exon 4 skipping is shown in the cDNA sequence of patient 4 with c.364-1G>A. (D) Patient P2 is heterozygous for c.886-3C>G, and 2-bp insertion of AG (blue) between exon 9 (yellow) and exon 10 (pink) is shown in the cDNA sequence. This insertion is caused by the introduction of a new splice acceptor site from c.886-4A to c.886-3C>G and subsequent inclusion of original splice acceptor site (c.886-2_-1AG) in the mature transcript.
Fig. 2.
Multiple alignment and amino acid conservation for a novel missense mutation c.397T>C (p.Cys133Arg). The cysteine at codon 133 is well-conserved among various species.
Table 1.
Manchester clinical diagnostic criteria for neurofibromatosis type 2
Table 2.
Primer sequences used in this study
Table 3.
Clinical features and molecular findings of the 7 patients who participated in this study
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