A case-control study of tyrosine phosphatase (PTPN22) confirms the lack of association with Crohn's disease.

In Crohn's disease (CD), the whole gastrointestinal tract can be affected by discontinuous and transmural inflammation. The terminal ileum and colon are especially prone to inflammation that comprises granulomata and later intestinal and perianal fistulas. Genome-wide linkage and epidemiological studies established genetic predisposition factors to CD. Recently, a variation of the intracellular protein tyrosine phosphatase nonreceptor-type 22 (PTPN22) was associated with several autoimmune diseases. Here, we analysed the functionally relevant polymorphism R620W (rs 2476601) of the PTPN22 gene in 146 patients suffering from CD using restriction fragment length polymorphism (RFLP) analyses. This study revealed evidence that PTPN22 variation may have no influence in the genetic predisposition to CD, at least not in another well-characterized Caucasian cohort.