The difference between the heterogeneity of the centromeric index and intrachromosomal asymmetry

Abstract

Intrachromosomal asymmetry, one of the two aspects of karyotype asymmetry, increases because of shifts of the centromere position from the median/submedian to terminal or subterminal. Conventional measures of asymmetry use comparisons with the most symmetrical karyotype and thus are an absolute measure of variation in the centromeric index. Conversely, the CVCI index, the coefficient of variation for the centromeric index, only evaluates the relative variation in the centromeric index. We performed a detailed analysis of the capability of the CVCI index and conventional measures of karyotype asymmetry to accurately characterize differences in intrachromosomal asymmetry. Our results show that the CVCI index is unable to accurately evaluate intrachromosomal asymmetry. In fact, the CVCI index evaluates a different measure than other conventional measures of karyotype asymmetry. Therefore, to avoid confusion, we propose that the variation evaluated by the CVCI index should be named heterogeneity of the centromeric index.