title: Retrovirus-like long-terminal repeat DQ-LTR13 and genetic susceptibility to type 1 diabetes and autoimmune Addison's disease.
abstract: Controversial data are available on the association between the retrovirus-like long-terminal repeat (LTR) DQ-LTR13 and genetic susceptibility to type 1 diabetes and other autoimmune diseases. We analyzed DNA samples from 315 type 1 diabetic patients, 166 autoimmune Addison's disease (AAD) patients, 1,054 healthy subjects, and 144 families of type 1 diabetic offspring. DQ-LTR13 was more frequent among patients than healthy subjects (P(c) < 0.0006), and a preferential transmission of DQB1*0302-LTR13(+) from parents to type 1 diabetic offspring was observed. DQ-LTR13 was in linkage disequilibrium (LD) with DQB1*0302 but not DQB1*0201. The presence of DQ-LTR13 increased the odds ratio of DQB1*0302 2.9- to 3.2-fold for type 1 diabetes and AAD. DRB1*0403 was absent in all of the 169 DRB1*04-positive patients but present in 27% (34 of 127) DRB1*04-positive healthy subjects (P(c) < 0.001). DQ-LTR13 was detected in 1 of 34 (3%) DRB1*0403-positive healthy subjects and 36 of 93 (39%) individuals carrying another DRB1*04 allele (P(c) = 0.002). Multivariate logistic regression analysis revealed that DQ-LTR13 is not independently associated with type 1 diabetes and AAD after correction for DQB1*0302 and DRB1*0403. Conversely, DQB1*0201, DQB1*0302, DRB1*0401, and DRB1*0403 were all significantly associated with disease risk also after correction for DQ-LTR13. We provide conclusive evidence that the genetic association of DQ-LTR13 with type 1 diabetes and AAD is primarily due to a LD with DQB1*0302 and DRB1*0403.
authors.affiliation: Department of Internal Medicine, University of Perugia, Via E. Dal Pozzo, I-06126 Perugia, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gambelunghe
authors.forename: Ingrid
authors.initials: I
authors.lastname: Kockum
authors.forename: Vittorio
authors.initials: V
authors.lastname: Bini
authors.forename: Giovanni
authors.initials: G
authors.lastname: De Giorgi
authors.forename: Federica
authors.initials: F
authors.lastname: Celi
authors.forename: Corrado
authors.initials: C
authors.lastname: Betterle
authors.forename: Roberta
authors.initials: R
authors.lastname: Giordano
authors.forename: Rossella
authors.initials: R
authors.lastname: Libè
authors.forename: Alberto
authors.initials: A
authors.lastname: Falorni
mesh_terms: D000224:Addison Disease / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000483:Alleles; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006683:HLA-DQ Antigens / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007223:Infant; D007558:Italy; D008875:Middle Aged; D010641:Phenotype; D012306:Risk; D020079:Terminal Repeat Sequences
chemical_list: D006683:HLA-DQ Antigens