Autoimmune disease
Autoimmune diseases are conditions in which your immune system mistakenly damages healthy cells in your body.
If someone have an autoimmune disease, his immune system mistakes parts of his body, such as your joints or skin, as foreign.
It releases proteins called autoantibodies that attack healthy cells.
Some autoimmune diseases target only one organ.
Type 1 diabetes damages your pancreas.
Other conditions, such as systemic lupus erythematosus, or lupus, can affect your whole body.
Research study
Researchers have suggested for a while that a number of immune diseases — including systemic lupus erythematosus, rheumatoid arthritis, and Sjögren’s syndrome — are more common in females than males.
In mammalian species, females typically carry two X chromosomes, while males possess one X and one Y chromosome.
Each of the X chromosomes is inherited from the parents.
In 1961, an English geneticist named Mary Frances Lyon argued that since females have two copies of the X chromosome, one of the X chromosomes is randomly inactivated during early embryonic development, in a process called X chromosome inactivation (XCI), to prevent the overexpression of X-linked genes in females.
In this process, epigenetic changes silence most genes on one X chromosome (epigenetics refers to the processes by which genes are influenced by the environment in which they operate).
XCI ensures a balance in gene expression, but scientists are also learning that it plays a role in various genetic disorders.
Issues such as incomplete inactivation (a.k.a. escape) or skewed inactivation can lead to the abnormal expression of genes, which contributes to diseases including X-linked disorders, certain cancers, and autoimmune conditions.
The reactivation of specific X-linked genes in response to XCI alteration varies across immune cell types, which is to say diverse molecular pathways are affected.
The resulting effects in autoimmune diseases are likely due to a combination of reactivation events in different cell types and global changes in gene expression.
The findings reinforce the molecular link between altered XCI and autoimmune diseases, and pave the way for possible new drugs to treat them in the future.
Another disease with a sex bias and linked to the X chromosome is Alzheimer’s disease.
Women seem to have a higher risk of getting it; worldwide, almost twice as many women have Alzheimer’s as men.
Ahead
In humans, the Y chromosome has been shrinking over time, so the X chromosome is possibly evolution’s best bet and thus plays a pivotal role in human health and disease.
Its evolutionary genomics and emerging insights into its participation in biological processes illuminate the complex interplay between genetic inheritance, epigenetic modifications, and disease manifestation.
Cracking all this to get the full picture could also lead us to new drugs and therapies.
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