Additional Information

In females, one of the X chromosomes in each cell is inactivated early in development to compensate for the difference in X-linked gene dosage between males and females. This inactivation occurs when one of the X chromosomes is packaged into a transcriptionally inactive heterochromatin structure called a Barr Body. Determination of X chromosome inactivation status is useful in the diagnostic analysis of nonrandom patterns.  Skewed patterns of inactivation in female carriers of a number of X-linked recessive disorders and asymptomatic female carriers of some X-linked dominant diseases have been observed.  X-inactivation studies are useful in diagnosing such disorders and determining carrier status of family members.