This post presents five interesting facts about Turner Syndrome (TS) and autoimmunity from the recent “Autoimmunity and Immune Dysregulation in Turner Syndrome” webinar, presented by Dr. Roopa Kanakatti Shankar. Dr. Shankar is an Assistant Professor of Pediatrics at The George Washington University School of Medicine and Health Sciences and the Director of the TS Program. These takeaways focus on the connections between TS and autoimmunity. Specific autoimmune conditions described in the webinar will be covered in a later post.
Note: This post is solely intended to inform and educate readers. It should not be considered medical advice and is not a substitute for recommendations or treatment from your healthcare provider(s).
1. Women have a 10-fold higher risk of acquiring an autoimmune disease.
Dr. Shankar discussed two hypotheses that might explain this. One hypothesis suggested that women with an autoimmune disease have shown higher rates of circulating cells missing an X chromosome. Additionally, since women have two X chromosomes, they undergo a naturally occurring, but random, phenomenon in which one X chromosome is inactivated. She described that there are hypotheses around this process of X inactivation that might be involved with autoimmune disease susceptibility.
2. Over time, scientists have found several key differences in the immune-cell profile in individuals with TS.
Studies investigating the immune profile of patients with TS began in 1981. Over time, one of the main findings across these studies showed that patients with TS had a lower ratio of helper T cells (i.e., CD4+ T cells) to effector T cells (i.e., CD8+ T cells). Helper T cells play a role in connecting invading pathogens with the adaptive immune system. Effector T cells have cytotoxic abilities, which means they attack invading pathogens. A more recent study found a connection to this low CD4+:CD8+ ratio to having a single X chromosome (i.e., isochromosome Xq).
3. Three genes have been found to play a significant role in the genetic basis for immune dysregulation: UTX, CD4oL, and FOXp3.
Put simply, immune dysregulation is a breakdown or change in immune system processes. Effects of the UTX gene, as described by Dr. Shankar, are decreased (i.e., downregulated) in patients with TS. This gene is associated with the development of immune cells important for the adaptive immune response. Additionally, it is functionally important for the clearance of chronic viral infections and chronic ear infections. The CD4oL gene is associated with an antibody condition called hyperIgM syndrome and several other autoimmune conditions. Finally, the FOXp3 gene may have a role in the development of regulatory T cells–T cells that are meant to regulate the other types of T cells to prevent them from going haywire. Loss of this gene may cause autoimmunity.
4. Epigenetics appears to play a role in the autoimmunity associated with TS.
Scientists have found a pattern across the genome–the whole set of genes in an individual–that may account for autoimmune disease susceptibility. Epigenetics describes the types of changes outside of the gene sequence that may change their structure or function. They found a specific signature called hypomethylation, which suggests overactive gene expression.
5. At this time, Dr. Shankar is not aware of any increased risk of acquiring COVID for people who have autoimmune conditions.
Autoimmune conditions, as Dr. Shankar mentioned, don’t actually put one at increased risk for infection. This is because, in these scenarios, the immune system is acting in a state of “overdrive.” There are some conditions like Addison’s disease, in which patients have insufficient amounts of adrenal hormones, that may put them at risk for developing autoimmune conditions. As a treatment, these patients will receive steroids to help calm their immune systems. Furthermore, this can put them at an increased risk for infection since steroids–specifically, high-dose steroids–act as immunosuppressants.
If you are interested in listening to the webinar to learn even more about TS and autoimmunity, please check out the webinar recording!
Written by Reyn Kenyon, TSF volunteer blog post writer and editor. Edited by Susan Herman, TSF volunteer and blog post editor.