MALDI-TOF Mass Spectrometry for Trisomy Detection

Matrix-associated laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is a tool currently under investigation for use in prenatal detection of abnormalities in chromosome number, such as trisomy 21. Because of its ability to detect extremely small differences in mass, even to the level of a single nucleotide difference, this method can be applied to the detection of single-nucleotide polymorphisms (SNPs), which when present in a heterozygous state, can yield quantitative information regarding chromosome status from diagnostic specimens such as amniotic fluid or chorionic villus samples. MALDI-TOF mass spectrometry has several potential advantages over traditional karyotyping methods, including its amenability to high-throughput analyses and its nonreliance on prior cell culture. The method described here is based on the MassEXTEND^� protocol developed by Sequenom, Inc., although any mass spectrometry platform sensitive enough to detect the small difference in mass between SNPs could be applied for this purpose.