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Diabetes Care. 2008 Mar;31(3):534-8. Epub 2007 Dec 4.

The protein tyrosine phosphatase nonreceptor 22 (PTPN22) is associated with high GAD antibody titer in latent autoimmune diabetes in adults: Non Insulin Requiring Autoimmune Diabetes (NIRAD) Study 3.

Author information

1
Department of Clinical Science, Sapienza University of Rome, Viale del Policlinico 155, 00161 Rome, Rome, Italy.

Abstract

OBJECTIVE:

We previously demonstrated the presence of two different populations among individuals with adult-onset autoimmune diabetes: those having either a high titer or a low titer of antibodies to GAD (GADAs). Protein tyrosine phosphatase nonreceptor type 22 (PTPN22) has been identified as a new susceptibility gene for type 1 diabetes and other autoimmune diseases. The aim of the present study was to evaluate whether the phenotypic heterogeneity of adult-onset autoimmune diabetes based on the GADA titer is associated with the PTPN22 C1858T polymorphism.

RESEARCH DESIGN AND METHODS:

Analysis for the C1858T polymorphism using the TaqMan assay was performed in 250 subjects with adult-onset autoimmune diabetes, divided into two subgroups with low (<or=32 arbitrary units) or high (>32 arbitrary units) GADA titers and 450 subjects with classic type 2 diabetes (from the Non Insulin Requiring Autoimmune Diabetes [NIRAD] Study cohort of 5,330 subjects with adult-onset diabetes) and in 558 subjects with juvenile-onset type 1 diabetes and 545 normoglycemic subjects.

RESULTS:

Genotype, allele, and phenotype distributions of the PTPN22 C1858T variant revealed similar frequencies in autoimmune diabetes with high GADA titer and juvenile-onset type 1 diabetes. An increase in TT and CT genotypes was observed in individuals with a high GADA titer compared with a low GADA titer, those with type 2 diabetes, and control subjects (P < 0.002 for all comparisons). The PTPN22 1858T allele and phenotype frequencies were increased in high GADA titer compared with a low GADA titer, type 2 diabetic, and control subjects (P < 0.001 for all comparisons, odds ratio 2.6).

CONCLUSIONS:

In adult-onset autoimmune diabetes, the PTPN22 1858T variant is associated only with a high GADA titer, providing evidence of a genetic background to clinical heterogeneity identified by GADA titer.

PMID:
18056891
DOI:
10.2337/dc07-1457
[Indexed for MEDLINE]

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