Electropherograms of microsatellite markers for three different DNA, (D07-D09), and for trisomy 21-DNA control (T21). On the y-axis is peak height and on the x-axis is the marker size in base-pairs. Marker alleles show up as major peaks and indicated in boxes underneath each allele are size in base-pair and the peak-area. a) Four individual electropherograms showing representative amplification of marker GDB:196999 (APP-dint). The blue peaks, for alleles 178 and 189, show the suspected copy-number variation in DNA sample D08. b) Four individual electrographs showing representative amplification of marker GDB:188463 (D21S265).