Polymorphisms in the CAG repeat--a source of error in Huntington disease DNA testing.
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.
Yu
S
S
Department of Molecular and Clinical Genetics, Royal Prince Alfred Hospital, Camperdown NSW, Australia.
Fimmel
A
A
Fung
D
D
Trent
R J
RJ
D000328:Adult; D020029:Base Pairing; D004247:DNA; D003951:Diagnostic Errors; D005820:Genetic Testing; D006801:Humans; D006816:Huntington Disease / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011237:Predictive Value of Tests; D018911:Trinucleotide Repeats
D004247:DNA