A comprehensive, statistically powered analysis of GAD2 in type 1 diabetes.
GAD2 maps to chromosome 10p11.23 and encodes the 65-kDa isoform of GAD65, a major autoantigen in type 1 diabetes. The genetic variation that influences expression of preproinsulin mRNA, encoding another major autoantigen in type 1 diabetes, has already been shown to be genetically associated with disease. Previous reports that have assessed the association of GAD2 with type 1 diabetes have not used a dense map of markers surrounding the gene and have relied on very small clinical sample sizes. Consequently, no definite conclusions can be drawn from their negative results. We have therefore systematically searched all exons, the 3' untranslated region (UTR), the 5' UTR, and the 5' upstream region of GAD2, for polymorphisms in 32 white European individuals. We have genotyped these polymorphisms in a maximum of 472 U.K. type 1 diabetic affected sib pair families exhibiting linkage to type 1 diabetes on chromosome 10p and have tested both single variants and haplotypes in the GAD2 region for association with disease. We subsequently followed up our results by genotyping a subset of these single-nucleotide polymorphisms in a maximum of 873 Finnish families with at least one affected child. Our results suggest that GAD2 does not play a major role in type 1 diabetes in these two European populations.
Johnson
Gillian C L
GC
Juvenile Diabetes Research Foundation/Wellcome Trust Diabetes and Inflammation Laboratory, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, U.K.
Payne
Felicity
F
Nutland
Sarah
S
Stevens
Helen
H
Tuomilehto-Wolf
Eva
E
Tuomilehto
Jaakko
J
Todd
John A
JA
D020413:3' Untranslated Regions / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D001483:Base Sequence / Q000235:genetics; D002879:Chromosomes, Human, Pair 10 / Q000235:genetics; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics*; D005060:Europe; D005091:Exons; D008040:Genetic Linkage; D014644:Genetic Variation; D005838:Genotype; D005968:Glutamate Decarboxylase / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D044465:White People / Q000235:genetics
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D007527:Isoenzymes; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2