Back Types of Chromosome Abnormalities There are many different types of chromosome abnormalities that require clinical care by a physician or other healthcare professional. Listed in the directory below are some, for which we have provided a brief overview. Numerical Abnormalities: Overview of Trisomies and Monosomies Down Syndrome (Trisomy 21) Trisomy 18 & 13 Turner Syndrome Structural Abnormalities: Deletions (Cri du Chat) and Duplications (Pallister Killian) Translocations Translocation Down Syndrome Other Arrangements: Rings and Inversions Mosaicism Mosaic Down Syndrome