Triticeae Genomics and Genetics, 2024, Vol.15, No.2, 77-87 http://cropscipublisher.com/index.php/lgg 82 cross-reactivity with related allergens in other cereals such as rye, barley, and oats (Baar et al., 2012).. The molecular characterization of Tri a 36, including its resistance to digestion and heat, makes it a valuable target for diagnostic tests and the development of specific immunotherapy strategies (Baar et al., 2012). Additionally, the quantification of CD immunogenic epitopes in gliadin sequences using techniques such as reversed-phase high-performance liquid chromatography (RP-HPLC) and database searches has provided insights into the variability of these epitopes among different wheat species (Ozuna and Barro, 2018). This variability is crucial for understanding the genetic predisposition to wheat sensitivities and for developing diagnostic tools that can accurately identify individuals at risk. 5 Celiac Disease and Wheat Genetics 5.1 Pathophysiology of celiac disease Celiac disease (CD) is a chronic autoimmune disorder triggered by the ingestion of gluten, a group of proteins found in wheat, barley, and rye. The disease primarily affects the small intestine, leading to inflammation and villous atrophy, which impairs nutrient absorption. Gluten proteins, particularly gliadins and glutenins in wheat, are resistant to gastrointestinal digestion, resulting in the formation of immunogenic peptides. These peptides are presented by antigen-presenting cells to T cells, leading to an inflammatory response that damages the intestinal mucosa (Moehs et al., 2019; Picascia et al., 2020). 5.2 Genetic predisposition to celiac disease The genetic predisposition to celiac disease is strongly associated with specific human leukocyte antigen (HLA) class II genes, particularly HLA-DQ2 and HLA-DQ8. Approximately 95% of individuals with celiac disease carry the HLA-DQ2 haplotype, while most of the remaining patients carry HLA-DQ8. These HLA molecules present gluten-derived peptides to CD4+ T cells, initiating the autoimmune response. However, the presence of these HLA alleles alone is not sufficient to cause the disease, indicating that other genetic and environmental factors also play a role in its pathogenesis (Moehs et al., 2019; Picascia et al., 2020). 5.3 Gluten proteins and celiac disease Gluten proteins, including gliadins and glutenins in wheat, hordeins in barley, and secalins in rye, are rich in proline and glutamine residues, making them resistant to complete digestion by gastrointestinal enzymes. The resulting peptides can cross the intestinal epithelium and be deamidated by tissue transglutaminase, enhancing their binding affinity to HLA-DQ2 and HLA-DQ8 molecules. This process is crucial for the activation of gluten-specific T cells and the subsequent inflammatory response. Recent research has focused on developing wheat varieties with reduced immunogenic gluten sequences to mitigate the adverse effects in celiac patients (Moehs et al., 2019; Picascia et al., 2020). 5.4 Diagnostic methods for celiac disease The diagnosis of celiac disease typically involves a combination of serological tests and intestinal biopsy. Serological tests detect specific antibodies, such as anti-tissue transglutaminase (tTG) and anti-endomysial antibodies (EMA), which are highly sensitive and specific for celiac disease. Positive serological tests are usually followed by an intestinal biopsy to confirm the diagnosis, which reveals characteristic histological changes such as villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes. Additionally, genetic testing for HLA-DQ2 and HLA-DQ8 can support the diagnosis, especially in cases with inconclusive serology or biopsy results (Moehs et al., 2019; Picascia et al., 2020). 6 Advances in Genetic Research on Wheat Allergies and Sensitivities 6.1. Genomic approaches to understanding wheat allergies Recent advancements in genomic technologies have significantly enhanced our understanding of wheat allergies and sensitivities. The advent of next-generation sequencing (NGS) has allowed for the comprehensive mapping of the wheat genome, facilitating the identification of genes associated with allergenic responses. For instance, the International Wheat Genome Sequencing Consortium has provided a fully annotated reference wheat-genome assembly, which has been instrumental in identifying and characterizing allergenic proteins such as prolamins and
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