A novel, convenient, and inexpensive approach for deriving ISCN (1985) relative lengths: validation by a morphometric study of 100 karyotyped metaphase cells.

The present study stemmed from a need for a rapid means of deriving reproducible chromosome measurements. An internal set of standards can serve as the basis for routine, easy, and reliable morphometric comparisons. In this study, a total of 100 karyotyped metaphases were analyzed using the Nestler Run-Mate, a computerized curvilinear measuring tool. The null hypothesis tested was that there are no significant differences between chromosomal relative-length values obtained via this previously untested approach and those cited in ISCN (1985). The results indicate that this new method is not only feasible and adequate but has advantage over the conventional approach, which requires the use of a projector and screen to measure chromosomes in unkaryotyped metaphase spreads; further, it is less expensive and easier than using computerized digitizing tablets, a conclusion supported by time-and-effort measurements. Immediately obvious applications include routine use in clinical cytogenetics laboratories, as well as for fractional length estimations in fluorescent in situ hybridization studies performed in research laboratories that do not have access to expensive automated instrumentation.