Novel polymorphism in the FMR1 gene resulting in a "pseudodeletion" of FMR1 in a commonly used fragile X assay

Thomas M. Daly, Arash Rafii Tabrizi, Rick A. Martin, Barbara A. Zehnbauer

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The fragile X syndrome is the most commonly inherited cause of mental retardation. Genetic diagnosis of this disease relies on the detection of triplet repeat expansion in the FMR1 gene on the X chromosome. Although the majority of disease in fragile X patients is due to mutations involving triplet repeat expansion, deletion of various portions of FMR1 has also been described in association with the fragile X syndrome. Here we describe a rare polymorphism in the noncoding region of FMR1 that mimics detection of a deletion in a commonly used assay for fragile X syndrome, which can result in misdiagnosis of the disease.

Original languageEnglish
Pages (from-to)128-131
Number of pages4
JournalJournal of Molecular Diagnostics
Issue number3
Publication statusPublished - Aug 2000
Externally publishedYes


ASJC Scopus subject areas

  • Molecular Biology

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