Indications

• Abnormal liver function tests

• Any child with a history of 3 or more antibiotic-treated cases of gastroenteritis while less than 6 months of age

• Arthritis

• Autoimmune conditions

• Ataxia

• Bloating

• Bone disease or loss of bone density

• Diarrhea

• Elevated liver function tests

• Evidence of impaired absorption of fat-soluble vitamins, iron, B12 or folic acid

• Failure to thrive (infants)

• Fatigue

• Fertility problems

• Hormonal problems

• Idiopathic neurological conditions  

• Individuals that have a first degree relative with celiac disease

• Individuals that have tested positive for the HLA DQ2/DQ8 genotypes

• Iron deficiency anemia

• Malnutrition

• Multiple Sclerosis

• Nutritional deficiencies

• Patients on a gluten-inclusive diet who have Type I diabetes

• Peripheral neuropathy

• Persistent gastrointestinal symptoms that are not associated with enteropathogens

• Rashes and skin problems

• Schizophrenia

• Thyroiditis

• Unexplained weight loss 

Contributing/causal factors

• Down syndrome

• IgA deficiency

• Thyroiditis

• Type I diabetes

Overview

The two methods most commonly used to diagnose CD are a blood test to check for abnormal levels of antibodies, and a biopsy of the small intestine. In many cases the results of these tests are inconclusive, especially in relatively young patients. Another method that helps to avoid this uncertainty, and which is not prone to the same issues, is DNA testing. 

The genetics of CD have been studied in detail. HLAs (Human Leukocyte Antigens) are used to train the immune system in the difference between foreign objects such as bacteria, and the body’s own cells. This prevents the immune system from attacking the body’s own cells, however in the case of autoimmune diseases such as CD, this system does not work properly. Many HLA gene variants exist throughout the human population, leading to different “haplotypes”. In order to develop CD, a person must have either the HLA-DQ2 or (less commonly) DQ8 haplotype. A person with a different haplotype, such as DQ3, will not develop CD. 

Not everyone who has the DQ2 or DQ8 haplotypes develops CD, however almost everyone (>99%) that develops CD has the DQ2 or the DQ8 haplotype. Therefore, while the genetic test alone cannot confirm a diagnosis of CD, it can either confirm it is highly likely (especially in combination with a blood test), or eliminate it completely. In this case, once the possibility of CD has been removed, the diagnosis can progress quickly onto other options in order to find the correct treatment. 

Practical

Sample required:

Saliva

Average processing time:

Maximum of 21 days

Research

• Babron, M., Nilsson, S., Adamovic, S., Naluai, Å T., Wahlström, J., Ascher, H., . . . Clerget-Darpoux, F. (2003). Meta and pooled analysis of European coeliac disease data. European Journal of Human Genetics, 11(11), 828-834. DOI: 10.1038/sj.ejhg.5201051

• Heel, D. A., Franke, L., Hunt, K. A., Gwilliam, R., Zhernakova, A., Inouye, M., . . . Wijmenga, C. (2007). A genome-wide association study for celiac disease identifies risk variants in the region harboring IL2 and IL21. Nature Genetics, 39(7), 827-829. DOI: 10.1038/ng2058

• Hunt, K. A., Zhernakova, A., Turner, G., Heap, G. A., Franke, L., Bruinenberg, M., . . . Heel, D. A. (2008). Newly identified genetic risk variants for celiac disease related to the immune response. Nature Genetics, 40(4), 395-402. DOI: 10.1038/ng.102

• Monsuur, A. J., Bakker, P. I., Zhernakova, A., Pinto, D., Verduijn, W., Romanos, J., . . . Wijmenga, C. (2008). Effective Detection of Human Leukocyte Antigen Risk Alleles in Celiac Disease Using Tag Single Nucleotide Polymorphisms. PLoS ONE, 3(5). DOI: 10.1371/journal.pone.000227