Protein tyrosine phosphatase non-receptor 22 (PTPN22), a gene found on chromosome 1p13, which encodes lymphoid protein tyrosine phosphatase (LYP) was found to be associated with susceptibility to type 1 diabetes in 2004. Protein tyrosine phosphatases such as LYP are responsible for preventing spontaneous T cell activation and they have the ability to prevent the response to antigen by dephosphorylating and inactivating T cell receptors. A single nucleotide polymorphism (SNP) in the PTPN22 gene can lead to susceptibility to autoimmune diseases such as type 1 diabetes because of a decrease in negative regulation of hyper-reactive T cells. The first complete resequencing of the human PTPN22 gene was carried out in 2005. This sequence was further analysed for polymorphisms associated with type 1 diabetes and a SNP at 1858bp in codon 620 was found. Two alleles referred to as 1858C and 1858T were identified and the 1858T variant was shown to occur more often in type 1 diabetes populations: 30.6% of people with type 1 diabetes compared with 21.3% healthy controls are heterozygous for the polymorphism p = 0.0006.

LYP is expressed in other cells in addition to T cells including natural killer (NK) cells, B cells, macrophages and dendritic cells (DCs), and so could very well also have an effect on the function of several immune cells.


Nobody has commented on this article

Commenting is only available for registered Diapedia users. Please log in or register first.