Exhaustive mutation analysis of the NF1 gene allows identification of 95% of mutations and reveals a high frequency of unusual splicing defects

Messiaen, Ludwine M.; Callens, Tom; Mortier, Geert; Beysen, Diane; Vandenbroucke, Ina; Van Roy, Nadine; Speleman, Frank; De Paepe, Anne

doi:10.1002/1098-1004(200006)15:6<541::AID-HUMU6>3.3.CO;2-E

Title

Exhaustive mutation analysis of the NF1 gene allows identification of 95% of mutations and reveals a high frequency of unusual splicing defects

Author

Messiaen, Ludwine M.

Callens, Tom

Mortier, Geert

Beysen, Diane

Vandenbroucke, Ina

Van Roy, Nadine

Speleman, Frank

De Paepe, Anne

Abstract

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders and is caused by mutations in the NF1 gene. Mutation detection is complex due to the large size of the NF1 gene, the presence of pseudogenes and the great variety of possible lesions. Although there is no evidence for locus heterogeneity in NF1, mutation detection rates rarely exceed 50%. We studied 67 unrelated NF1 patients fulfilling the NIH diagnostic criteria, 29 familial and 38 sporadic cases, using a cascade of complementary techniques. We performed a protein truncation test starting from puromycin-treated EBV cell lines and, if no mutation was found, continued with heteroduplex, FISH, Southern blot and cytogenetic analysis. We identified the germline mutation in 64 of 67 patients and 32 of the mutations are novel. This is the highest mutation detection rate reported in a study of typical NF1 patients. All mutations were studied at the genomic and RNA level. The mutational spectrum consisted of 25 nonsense, 12 frameshift, 19 splice mutations, six missense and/or small in-frame deletions, one deletion of the entire NF1 gene, and a translocation t(14;17)(q32;q11.2). Our data suggest that exons 10a-10c and 37 are mutation-rich regions and that together with some recurrent mutations they may account for almost 30% of the mutations in classical NF1 patients. We found a high frequency of unusual splice mutations outside of the AG/GT 5¢ and 3¢ splice sites. As some of these mutations form stable transcripts, it remains possible that a truncated neurofibromin is formed.

Language

English

Source (journal)

Human mutation. - New York, N.Y.

Publication

New York, N.Y. : 2000

ISSN

1059-7794

DOI

10.1002/1098-1004(200006)15:6<541::AID-HUMU6>3.0.CO;2-N

10.1002/1098-1004(200006)15:6<541::AID-HUMU6>3.3.CO;2-E

Volume/pages