enon occurring repeatedly in approximately the same way. Great deviations from the so-called “normal pattern” are termed abnormalities. Abnormalities can be intuitively viewed as very extreme values or “outliers” on a frequency-class plot (C u r c i c et al., 2006). They can be related to genetic events such as gene mutations or chromosomal aneuploidies and translocations (malformations), as well as to exogenous factors such as certain chemicals, viruses, radiation, and hyperthermia (disruptions) (G i l b e r t, 2003).