Molecular and genetic advances in celiac disease [Çölyak hastali?indaki moleküler ve genetik gelişmeler]

Celiac disease is a multifactorial genetic disease that is associated with both environmental and genetic factors; it appears in sensitive individuals who have intake of wheat gluten and similar grain proteins in their diets. Currently, it is agreed that celiac patients have an innate genetic predisposition to the disease, and this predisposition changes to disease as a result of environmental factors. Although there is no treatment for celiac disease, it is believed that elimination of gluten from the diet is the only precaution that can be taken against it. In childhood, the symptoms of celiac disease usually appear as chronic diarrhea, growth failure, abdominal distension and iron deficiency; in adulthood, it appears in a weaker grade. It is known that celiac disease affects 1% of the European and North American populations. The disease is characterized by the presence of anti-tissue transglutaminase (anti-tTG) and anti-endomysial (EmA) antibodies. However, certain diagnosis is made through biopsy of the small intestine, which provides determination of typical histological anomalies. Looking at the molecular mechanisms of celiac disease, it is strongly correlated with DQ2 and DQ8 molecules, which are HLA-class II protein molecules. These molecules are coded by alleles at the HLA-DQA1 and HLA-DQB1 loci. Although HLA-DQ2 haplotype is a very important locus in celiac disease, it is not the only one that plays a role in the formation of the disease. It is thought that this locus is responsible for only 40% of patients, and so there must exist other loci that affect manifestation of the disease. A number of studies have at different times put forward 12 alternative loci, from CELIAC2 to CELIAC13, as being correlated with celiac disease. This article focuses on a current view regarding the molecular mechanisms of celiac disease and the various candidate genes and loci found by many researchers to be correlated with the disease