Barr body is a compact structure of chromatin formed in the nuclei of mammalian females as a means to allow sex dosage compensation. A person with Turner syndrome will have no Barr bodies due to them only have 1 X chromosome. Instead of having a set of 44 autosomes + 1 pair of sex chromosomes (either XX or XY) - the normal human karyotype, the person has only 44 autosomes + 1 X chromosomes.