Visual classification of banded human chromosomes. III. Classification and karyotyping of density profiles described by band transition sequences.

Band transition profiles (BT-profiles) representing extracted band pattern features of 898 density profiles of banded chromosomes were classified and karyotyped by a cytogeneticist in order to investigate how much information was lost by substituting for the original density profiles their extracted features. The results were evaluated and compared with visual classification and karyotyping of the same 898 density profiles from which the BT-profiles were derived. Six per cent errors were made in classification of isolated BT-profiles and 0.7% errors were made in karyotyping BT-profiles. These error rates were comparable to the corresponding error rates in classifying and karyotyping density profiles, which were 5% and 0.5%, respectively. It is concluded that most of the important band pattern information of the density profiles is retained in the BT-profiles, and it is supposed that the condensed BT-sequences (from which the BT-profiles are derived) constitute a sufficient and appropriate basis for automated karyotyping.