We investigated frequencies of single nucleotide polymorphisms (SNPs) in the candidate genes protein tyrosine phosphatase, non-receptor type 22 (PTPN22), B-cell scaffold protein with ankyrin repeats (BANK1), B lymphocyte kinase (Blk), and Fc gamma receptor class IIB (FCGR2B), which have been found to be associated with other autoimmune diseases, CD1A and CD1E, important for antigen presentation of glycolipids, and transient axonal glycoprotein 1 (TAG-1), which is associated with responsiveness to intravenous immunoglobulin in patients with chronic inflammatory demyelinating polyneuropathy.
In this paper, we discuss the association of PTPN22 with autoimmunity, the biochemistry of the PTPN22-encoded phosphatase, and the molecular mechanism(s) by which the disease-predisposing allele contributes to the development of human disease.
In 33 of the 416 patients (8%), the concomitant autoimmune disease was known to be associated with PTPN22 1858T; these patients were excluded prior to analysis.
Together with previous data showing associations with other autoimmune diseases, our findings provide further evidence that the PTPN22 gene plays a role in the pathogenesis of a subgroup of autoimmune diseases.
A gain-of-function mutant of the lymphoid phosphatase Lyp (PTPN22) has recently been implicated in type 1 diabetes and other autoimmune diseases, suggesting that small-molecule inhibitors of Lyp could be useful for the treatment of autoimmunity.
The following terms were used for the search: [subclinical hypothyroidism OR thyroid autoimmunity OR thyroperoxidase antibody (TPO-Ab) OR thyroglobulin antibodies (Tg-Ab)] AND (levothyroxine OR euthyrox) AND [pregnancy outcome OR miscarriage OR abortion OR pregnancy loss OR preterm birth OR premature delivery OR early labo(u)r].
Confirmation of the roles of CTLA4 and PTPN22 as general immune function modulators with a nonlinear dose-response effect on autoimmunity, and confirmation of the role of IL2RA, which may act via a regulatory T cell subset on immune disease risk.
<sup>131</sup>I-IGD was more common in patients with pre-treatment direct or indirect signs of autoimmunity: positive anti-TPO (p < 0.05), glandular hypoechogenicity, TRAbs within reference range, diffuse uptake on 99mTc-pertechnetate scans (p < 0.05), findings that may increase the risk tenfold.
Furthermore, the Q263 variant conferred protection against human systemic lupus erythematosus, reinforcing the proposal that inhibition of LYP activity could be beneficial in human autoimmunity.
Expert commentary: Current data suggest that PTPN22 can be a promising target for therapeutic interventions and identification of at-risk subjects in autoimmune diseases such as T1D.
A single nucleotide polymorphism (SNP) of the gene encoding protein tyrosine phosphatase type 22 (PTPN22 620W) has recently been described as a strong common genetic risk factor for human autoimmune disease.
In this review, we discuss these differences and the factors that may account for them, as well as show how an integrated approach can lead to a more complete understanding of the mechanisms that promote autoimmunity in the context of the PTPN22 1858T risk variant.
These results are consistent with the hypothesis that individuals lacking the C allele of PTPN22 may have reduced capacity to downregulate T-cell responses and may therefore be more susceptible to autoimmunity.
It has been suggested that the *T variant of PTPN22 inhibits T cell receptor signaling leading to failure to delete autoreactive T cells during intrathymic selection resulting in increased susceptibility to autoimmune disorders.
We have recently shown that thyroperoxidase antibody positivity impairs the thyroidal response to hCG stimulation, which may suggest that this is a mechanism through which thyroid autoimmunity acts as a risk factor for thyroid disease.