A rapid method to study the relationship between IDDM and HLA-DQ beta 57 Asp

The promoter region of the CTLA4 gene is associated with type 1 diabetes mellitus

The CTLA4 (cytotoxic T lymphocyte associated antigen-4) gene encodes the T cell receptor involved in the control of T cell proliferation and mediates T cell apoptosis. C-T polymorphism is present at position -318 from the ATG start codon in the promoter region of the gene. We report a study on the polymorphism in 347 unrelated children with type 1 diabetes mellitus (DM) (age at diagnosis 7.2+/-3.8 years) and their 260 healthy siblings as controls. Genotype C/C conferred a risk of type 1 DM (RR = 2.02, 95% CI 1.32-3.10, pc = 0.0033). The gene frequency of the C allele was higher in patients (RR = 1.91, 95% CI 1.28-2.84, pc = 0.0026). The gene frequency and phenotype frequency of the T allele were negatively associated with type 1 DM (RR = 0.52, 95% CI 0.35-0.78, pc = 0.0026 and RR = 0.49, 95% CI 0.32-0.76, pc = 0.0022, respectively). The frequency of genotype C/T was lower in patients (RR = 0.50, 95% CI 0.32-0.78, pc = 0.0051). This study demonstrates that nucleotide -318 C-T polymorphism of the CTLA4 gene is associated with type 1 DM. The promoter allele -318 C confers a risk of type 1 DM but allele -318 T confers protection against this disease.

HLA-DRB1 and -DQB1 polymorphism in liver recipients: relationship between HLA-DQB1*0302 allele frequency and acute rejection

Polymorphism of HLA-DRB1 and HLA-DQB1 loci was performed in fifty-three orthotopic liver graft recipients as well as in 108 unrelated healthy controls. Nonradioactive SSOPs were used to study PCR-amplified DNA from peripheral blood lymphocytes and biopsied material. The comparison frequency for DQB1 alleles did not reveal any significant differences between the total group of liver recipients and controls. However, when the liver recipients were subgrouped according to their rejection episode manifestations, increased and significant frequencies were observed for HLA-DQB1*0302 allele in patients showing acute rejection episodes compared to healthy controls or patients without acute rejection. This relationship did not appear influenced by the amino acid beta alanine residue in the 57th position. On the other hand, the study of the DRB1 allele frequencies did not show significant differences in any study. These results suggest that HLA-DQB1 genes could be important in the liver graft alloresponses, opening a way to a better understanding of the special tolerance state, normally observed in this type of transplant, leading us to consider the possible HLA-DQB1*0302 allele effect on tolerance rupture.