Computer counting of lithium-treated metaphase chromosomes a population survey technique
✍ Scribed by Curt Freed
- Publisher
- Elsevier Science
- Year
- 1973
- Tongue
- English
- Weight
- 871 KB
- Volume
- 6
- Category
- Article
- ISSN
- 0010-4809
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✦ Synopsis
Automatic counting of chromosomes by computer is a feasible technique for screening human populations for aneuploidy. This paper presents a system which has been developed around a new lithium-treated chromosome preparation. 35 mm negatives of metaphase chromosome spreads are scanned fully automatically; chromosomes are distinguished from nonchromosomes to get the count for a given spread and then thirty spread counts per patient are pooled in a histogram to find the true chromosome complement. Presumptive sex diagnosis is also made by comparing A-C and D-G group counts. Results are presented from a normal male, a normal female and X0-XYY mosaic.
Considerable effort has been expended on automation of chromosome karyotyping with a goal of at least classifying chromosomes into groups by length and centromere position (1-4). Particular attention has been paid to the difficulties of dealing with the irregularities of a standard colchicine chromosome preparation, especially the problems of bent arms, of uncertainties about centromere position, of fragmentation of chromosomes by differential staining, and of overlapping and touching chromosomes. Because of the limited success of completely automatic computer techniques, Neurath and others have designed systems around operator intervention to correct errors (5). Still, only carefully selected spreads have been successfully karyotyped. Rutovitz has estimated only ten percent of metaphase spreads are suitable (3). The efforts to resolve touches and overlaps are mainly an effort to salvage a larger fraction of these spreads.
New chromosome preparation techniques may help. Quinacrine labeling gives more distinguishing information about individual chromosomes and may make computer karyotyping easier (6).
Much less attention has been given to the problem of automatic counting of chromosomes even though aneuploids comprise most of the clinically relevant syndromes. Part of the reason might be that to do a reliable count one must solve many of the same pattern recognition problems. Chromosomes must be distinguished