Skewing of X chromosome inactivation in autoimmunity

Approximately 5% of the population in Western countries is affected by autoimmune diseases (AID), with a significantly higher prevalence in women. Genetic factors are known to be crucial determinants of susceptibility as shown by family and twin studies, although no specific genes predisposing women to autoimmunity have been identified thus far. Several studies indicate that X chromosome abnormalities, such as inactivation patterns, characterize some female-predominant AID. We herein review the most recent evidence on the role of the X chromosome in the breakdown of immune tolerance and discuss its potential implications. Future efforts will help to identify specific X chromosome regions containing candidate genes for disease susceptibility.