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Polymorphisms in the CAG repeat – a source of error in Huntington disease DNA testing
Author(s) -
Yu S,
Fimmel A,
Fung D,
Trent RJ
Publication year - 2000
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1034/j.1399-0004.2000.580607.x
Subject(s) - huntington's disease , allele , genetics , biology , trinucleotide repeat expansion , genotype , polymerase chain reaction , microbiology and biotechnology , disease , gene , medicine
Five of 400 patients (1.3%), referred for Huntington disease DNA testing, demonstrated a single allele on CAG alone, but two alleles when the CAG+CCG repeats were measured. The PCR assay failed to detect one allele in the CAG alone assay because of single‐base silent polymorphisms in the penultimate or the last CAG repeat. The region around and within the CAG repeat sequence in the Huntington disease gene is a hot‐spot for DNA polymorphisms, which can occur in up to 1% of subjects tested for Huntington disease. These polymorphisms may interfere with amplification by PCR, and so have the potential to produce a diagnostic error.