In normal females, number of Barr bodies is one less than the number of X chromosomes. One Barr body means the female has two $\mathrm{X}$ chromosomes. Turner's syndrome $(44+\mathrm{X} 0)$ is a genetic disorder that affects only females. In this condition, cells of the affected female possess only one $\mathrm{X}$ chromosome, instead of two. Due to the presence of only one $\mathrm{X}$ chromosome, no Barr body is present in females suffering from Turner's syndrome.