This web page was produced as an assignment for Genetics 677, an undergraduate course at UW-Madison.

What is Celiac Disease?

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Celiac Disease (CD) is a lifelong inherited autoimmune disease that is known to damage the lining of the small intestine.  Affecting about 1 % of children and adults world‐wide [1], the prevalence of CD is most common in women, caucasians, and those who have a family member with the disease [4].  It can appear at any time throughout an individual’s life and, if untreated, is known to cause a range of long‐term conditions such as anemia, early onset osteoporosis, nervous system disorders, intestinal lymphomas, and gall bladder malfunction [2].  The main cause of this disease is gluten, a protein found in grains such as wheat, barley, and rye.  When individuals with CD consume food containing gluten, their immune system creates a toxic reaction that ultimately damages the villi lining the small intestine.  Because these villi are critical in absorbing nutrients from the food that we eat, their damage causes serious malnourishment no matter how much food is later consumed [4].  Aside from the lack of vitamin and mineral absorption, there are classic symptoms associated with CD such as abdominal cramping, intestinal gas, stomach bloating, weight loss or weight gain, and chronic diarrhea [2].  While these classic symptoms lead some individuals to a diagnosis, unfortunately most symptoms vary greatly and are sometimes not present at all.  This inconsistency makes the diagnosis of CD extremely difficult, leading to the estimation that for every individual diagnosed with CD, there are at least 5 or 6 more individuals in the population who continue to suffer without correct CD diagnosis [4].  There is no known cure for CD, requiring affected individuals to strictly follow a gluten‐free diet.  When gluten is completely removed from the diet, the small intestine is allowed to heal and nutrients can continue to be absorbed.


The image below shows the intestinal lining of a healthy patient (on the left) as well as a patient suffering from CD (on the right).  In a healthy patient, nutrients are absorbed by the villi lining the inside of the small intestine and continue to travel into the bloodstream.  However, in a person with CD, these villi lining the small intestine are damaged due to an inflammatory response to ingested gluten.  These damaged villi do not function normally in absorption, allowing for fewer nutrients to travel into the bloodstream.  

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How is HLA-DQA1 related to Celiac Disease?

Many genes have been linked to CD in some manner, expanding on the great complexity of this disease.  HLA Class II histocompatibility antigen DQ alpha 1 presursor (HLA-DQA1) exists as part of a heterodimer, consisting of an alpha (DQA) and a beta subunit (DQB) [7].  Found in the membrane and expressed on antigen presenting cells (APC), this gene plays a central role in the immune system. Specifically, HLA-DQA1 presents peptides that are derived from extracellular proteins for recognition by the CD4 T-cells [7].  Research has determined that HLA‐DQA1 is associated with a greatly increased risk of CD, demonstrated by results finding 97% of CD patients possessing both HLA‐DQA1 and HLA‐DQB1 [5].  For more information about the HLA-DQA1 gene click here, or see the gene tab in the main menu.


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This figure shows the normal role that HLA-DQA1 plays in presenting peptides to T-cells.


Celiac Disease in the media


Below is a YouTube video of The View's Elizabeth Hasselbeck discussing her life with Celiac Disease.  Her doctor appears as a guest and provides information on symptoms, treatments, and healthy gluten-free food options for those suffering with CD.




References:

  1. http://knol.google.com/k/celiac‐disease#
  2. Celiac Disease Foundation. Celiac Disease General Brochure. Print.
  3. Bizzaro, N., R. Tozzoli, D. Villalta, M. Fabris, and E. Tonutti. "Cutting‐Edge Issues in Celiac Disease and in Gluten Intolerance." Clinical Reviews in Allergy and Immunology 15.1 (1997): n. pag. Web. 7 Feb 2011 http://www.springerlink.com.ezproxy.library.wisc.edu/content/j17wu631711u1027/fulltext.pdf.
  4. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001280
  5. http://www.ncbi.nlm.nih.gov.ezproxy.library.wisc.edu/pubmed/17919990
  6. http://www.youtube.com/watch?v=4v-9U8GbLu0&playnext=1&list=PLBDEAB0B066F2D8CC
  7. Gene Cards- http://www.genecards.org/ 
  8. Homologene- http://www.ncbi.nlm.nih.gov/homologene
  9. BLAST- http://blast.ncbi.nlm.nih.gov/Blast.cgi
  10. PubChem- http://pubchem.ncbi.nlm.nih.gov/ 




Website Author: Cassie Bac
Email: bac@wisc.edu
Last updated: 5-8-11
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