A Single-Tube, EuroClonality-Inspired, TRG Clonality Multiplex PCR Aids Management of Patients with Enteropathic Diseases, including from Formaldehyde-Fixed, Paraffin-Embedded Tissues.

Celiac disease is a chronic inflammation of the small intestine with villous atrophy that can become refractory to a gluten-free diet. Two categories of refractory celiac disease can be distinguished by the phenotype of intraepithelial lymphocytes and the status of TRG genes. Their distinction is important because 30% to 50% of type II but only 0% to 14% of type I evolve to an aggressive enteropathy-associated T-cell lymphoma and therefore require intensive treatment. Currently, differential diagnosis integrates immunohistochemistry, immunophenotyping, and TRG clonality analyses, but each has limitations. A single-tube multiplex TRG PCR (ECN) was prospectively compared to an in-house two-tube TRG PCR (N2T) in 73 samples, including 67 cryopreserved intestine tissues. Thirteen formalin-fixed, paraffin-embedded (FFPE) samples were also analyzed retrospectively. The ECN PCR had comparable efficiency to detect major clonal rearrangements in highly infiltrated tissues from T-cell lymphoproliferative disorders and type II refractory celiac disease and to detect the persistence of minor clones in type II refractory celiac disease follow-up samples. The ECN PCR abolished the risk of amplification of false-positive weak clonal rearrangements in cryopreserved specimens and allowed improved detection of clonal rearrangements in DNA from FFPE samples. The ECN PCR allows robust assessment of cryopreserved and FFPE digestive tissues at diagnosis and follow-up of enteropathies with villous atrophy, thus guiding therapeutic management.