The Principles of Clinical Cytogenetics - Extra Materials - Springer

482 Daynna Wolff and Stuart Schwartz
Fig. 18. Array CGH analysis of a subject with monosomy 1p36. (A) Subject DNA is compared to a control
DNA sample using CGH. The microarray is constructed from 97 large insert clones from the most distal 10.5
Mb of 1p36 (84). (B) Ratio of subject to control DNA is plotted for each large insert clone. Clones 1–97 (left)
represent the 1p36 contig. Clones 98–144 (right) represent each telomere (41 sites), 3 clones for the X chromosome,
and 3 clones for the Y chromosome. Deletion is indicated by those ratios that fall below –0.5. Gain of
DNA copy number are those ratios above 0.5. Equal DNA copy numbers between subject and control are
around zero (85). Shown is subject 11 from ref. 85. (C) Schematic of 1p36 showing location of genetic markers.
The red line indicates deletion, whereas the green line indicates retention (normal) as determined by array
CGH. This patient has a terminal deletion approx 6.75 Mb in size. (Courtesy of Dr. Shaffer and Dr. Yu, Washington
State University, Spokane and Baylor College of Medicine, Houston.)
ordered on the fibers. This provides a much higher spatial resolution and allows for correct orientation
precise mapping of the probes.
Primed In Situ Labeling
Primed in situ labeling (PRINS) is essentially PCR on a slide (89). Primers of interest are hybridized
on a slide and then subjected to cycles of denaturation, reannealing, and elongation that are used to
incorporate labeled nucleotides. The labels are then detected fluorescently, or labeled nucleotides are
incorporated during the reaction. This technology is utilized both clinically and for research purposes. It
has been used successfully with both repetitive and single-copy probes. One of the more useful applications
of this technologies is differentiation of the α-satellite sequences for chromosomes 13 and 21,
something that cannot be accomplished with traditional FISH. (See Fig. 21.)