Sexual dimorphism has been reported in various human diseases including autoimmune diseases

neurological diseases

pulmonary arterial hypertension

and some types of cancers

although the underlying mechanisms remain poorly understood. The long noncoding RNA (lncRNA) X-inactive specific transcript (

XIST

) is involved in X chromosome inactivation (XCI) in female placental mammals

a process that ensures the balanced expression dosage of X-linked genes between sexes.

XIST

is abnormally expressed in many sex-biased diseases. In addition

escape from

XIST

-mediated XCI and skewed XCI also contribute to sex-biased diseases. Therefore

its expression or modification can be regarded as a biomarker for the diagnosis and prognosis of many sex-biased diseases. Genetic manipulation of

XIST

expression can inhibit the progression of some of these diseases in animal models

and therefore

XIST

has been proposed as a potential therapeutic target. In this manuscript

we summarize the current knowledge about the mechanisms for

XIST

-mediated XCI and the roles of

XIST

in sex-biased diseases

and discuss potential therapeutic strategies targeting

XIST

.