X chromosome, a sex chromosome that in humans and many other animals is present in both sexes, appearing singly in the cells of normal males and in duplicate in the cells of normal females. The chromosome is present in all of the female gametes and in half of the male gametes, is much larger than the Y chromosome, and has many sex-linked genes associated with clinically significant disorders, such as hemophilia, Duchenne’s muscular dystrophy, and Hunter’s syndrome. Compare Y chromosome.
