Is Celiac Disease Substantially Underestimated?

Celiac.com 09/18/2013 - New tests and new histological criteria for diagnosing celiac disease, along with changing perspectives on the disease's natural history are causing a number of researchers to question past prevalence estimates for celiac disease.

A team of researchers recently set out to establish a more accurate estimate of celiac disease rates by using a new serogenetic method.

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The research team included Robert P Anderson, Margaret J Henry, Roberta Taylor, Emma L Duncan, Patrick Danoy, Marylia J Costa, Kathryn Addison, Jason A Tye-Din, Mark A Kotowicz, Ross E Knight, Wendy Pollock, Geoffrey C Nicholson, Ban-Hock Toh, Matthew A Brown and Julie A Pasco.

They are variously affiliated with the Walter and Eliza Hall Institute of Medical Research, the Department of Medical Biology at the University of Melbourne, the Department of Gastroenterology at The Royal Melbourne Hospital, Melbourne Health in Parkville, Australia, ImmusanT Inc., One Kendall Square, Building 200, LL, Suite 4, Cambridge, MA, USA, the School of Medicine at Deakin University in Geelong, Australia, Healthscope Pathology in Melbourne, Australia, the Human Genetics Group at the University of Queensland Diamantina Institute, Level 5, Translational Research Institute in Woolloongabba, Australia, Endocrinology at Royal Brisbane and Women’s Hospital, Herston, Australia, the NorthWest Academic Centre of the Department of Medicine at The University of Melbourne in St Albans, Australia, Geelong Gastroenterology, Level 1, in Geelong, Australia, the Rural Clinical School at the School of Medicine of The University of Queensland in Toowoomba, Australia, and Roche Diagnostics Australia, in Castle Hill, Australia.

The researchers assessed human leukocyte antigen (HLA)-DQ genotype in 356 patients with biopsy-confirmed celiac disease.

They did the same for two age-stratified, randomly selected community groups of 1,390 women and 1,158 men, who served as controls. They tested and screened all patients for celiac-specific serology.

They found that only five patients with biopsy-confirmed celiac disease lacked the susceptibility alleles HLA-DQ2.5, DQ8, or DQ2.2, and four of these patients had been misdiagnosed. HLA-DQ2.5, DQ8, or DQ2.2 was present in 56% of all women and men in the community cohorts.

Transglutaminase (TG)-2 IgA levels were abnormal in 4.6% of the community women, and in 6.9% of the community men. Composite TG2/deamidated gliadin peptide (DGP) IgA/IgG were abnormal in 5.6% of the community women and in 6.9% of the community men.

But in the screen-positive group, only 71% of women and of women and 65% of men possessed HLA-DQ2.5, DQ8, while 75% of women and 63% of men possessed DQ2.2.

Medical review was possible in 41% of seropositive women and 50% of seropositive men, and led to biopsy-confirmed celiac disease in 10 women (0.7%) and 6 men (0.5%). Based on relative risk for HLA-DQ2.5, DQ8, or DQ2.2, celiac disease affected 1.3% of men and women with positive TG2 IgA screens, and 1.9% of women and 1.2% of men with positive TG2/DGP IgA/IgG screens

Serogenetic data from these community cohorts indicated that testing screen positives for HLA-DQ, or carrying out HLA-DQ and further serology, could have reduced unnecessary gastroscopies due to false-positive serology by at least 40% and by over 70%, respectively.

Requiring biopsy confirmation based on TG2 IgA serology leads to substantial underestimations of the community prevalence of celiac disease.

Testing for HLA-DQ genes and affirmative blood results could reduce the numbers of unnecessary gastroscopies.

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