Most of the genetic disorders you have learned about are the result of a change in DNA sequence, as with cystic fibrosis, or the presence of an extra chromosome, as with Down syndrome. The exception is Turner's syndrome. Women with Turner's syndrome have only 45 chromosomes. They are missing an X chromosome. This disorder is the only case in which a person can survive with one less chromosome. What does this tell you about how genetic information is inherited in humans?