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Title: Analysis of a new mutation in the neurofibromatosis (NF1) gene leads to characterization of an exon in an NF1-related gene on chromosome 15

Journal Article · · American Journal of Human Genetics
OSTI ID:134222

A mutation search in the NF1 gene, using heteroduplex analysis of exons amplified from 52 patients with NF1, identified one patient with an unusual heteroduplex pattern in exon 24. The heteroduplex pattern was also present in the patient`s affected father, but not in her unaffected mother or in 50 individuals with and 50 without NF1. We characterized the familial mutation by cloning and sequencing the 159 bp exon 24, which encodes part of a GAP-related domain, and about 40 bp of each flanking intron. The mutation responsible for the heteroduplex formation is a single base deletion in codon 1416 that causes a frameshift and the immediate formation of a stop codon. Exon 24 was amplified using PCR conditions and primers previously reported to amplify only from the NF1 locus on chromosome 17. In our family however, multiple unrelated clones each with sequence differing from wild-type by one 3 bp deletion and 10 single base changes suggested that the clones contained sequence from one of the NF1-related loci on chromosomes 2, 12, 14, 15, 21, or 22. We sequenced the PCR product from monochromosomal somatic cell hybrids and found the chromosome 15 product to be identical to the {open_quotes}mutant{close_quotes} clones. The sequence has {approximately}95% homology with the NF1 exon 24 but only {approximately}10% homology with published sequence for a chromosome 15 NF1-related locus amplified from a neuroblastoma. A possible second NF1-related locus on chromosome 15 could therefore also confound NF1 mutation analysis.

OSTI ID:
134222
Report Number(s):
CONF-941009-; ISSN 0002-9297; TRN: 95:005313-0958
Journal Information:
American Journal of Human Genetics, Vol. 55, Issue Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
Country of Publication:
United States
Language:
English