Abnormal chromosomes. Computer artwork of a chromosomal aberration. Each chromosome is made up of two chromatids, which are linked at a region called the centromere. The chromosome at left has an extra portion of chromatid attached to it (lower centre). This sort of aberration has consequences during cell division and the production of gametes. Chromosomal aberrations can include deletion, duplication, translocation or inversion. They can occasionally result in increased genetic diversity, but usually they have negative effects and are often fatal. Chromosomes are only X-shaped during replication.