Biomedical Engineering Reference
In-Depth Information
Fig. 3. Schematic illustration of the single allele base extension reaction (SABER)
and standard MassARRAY assays. Maternal plasma detection of the paternally inher-
ited fetal specific
-thalassemia mutation, IVS2 654 C>T, is presented as an illustra-
tive example. Maternal plasma is first amplified by polymerase chain reaction (PCR).
The PCR products are subjected to base extension by the standard and SABER proto-
cols. The standard protocol involves the base extension of both the mutant fetal allele
(the T allele) and the background allele (the C allele), whereas the SABER method
only extends the fetal specific mutant allele, because only ddATP is supplied. The
base extension reactions are terminated by ddNTPs, indicated in square boxes. The
extension products of the standard protocol include a predominance of the nonmutant
allele (unfilled block arrows), with a small fraction of the fetal specific mutant allele
β
