Measurement of polymorphic trinucleotide repeats in the androgen receptor gene by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Trinucleotide repeats are polymorphic in normal individuals. CAG repeats in the X-linked androgen receptor gene were counted by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS). A region of approximately two hundred base-pairs containing the repeats was amplified by polymerase chain reaction, then measured after a simple purification procedure. The single-charged molecular ion species was detected using 0.1 pmol of DNA sample and the number of repeats was determined from the molecular mass. The results indicated that MALDI/TOF-MS is a high-throughput alternative to polyacrylamide gel electrophoresis for precise determination of polymorphic trinucleotide repeats. Copyright 1999 John Wiley & Sons, Ltd.