Association of CTLA-4 gene polymorphism in Jordanian type 1 diabetic patients

الملخص EN

Objective : to study the association between type 1 diabetes mellitus and the allelic polymorphism of the Cytotoxic T Lymphocyte Associated-4 gene in a Jordanian population.

Methods : we studied 50 Jordanian type 1 diabetes mellitus and 50 normal subjects at King Hussein Medical Centre and Princess Haya Biotechnology Centre, during the period of September 2008 and September 2010, to determine the association between the Single Nucleotide Polymorphism A/G and–C / T and type 1 diabetes mellitus.

Chi-squared test and Fisher exact tests were used to analyze the data.

P value < 0.05 was considered significant.

Result : the frequency of heterozygous genotype AG= 42 %, homozygous for the wild type allele genotype AA = 50 %.

Homozygous genotype of the mutant allele GG = 8 %.

The allele frequency for the wild allele A = 71 %, and for mutant allele is G = 29 %, with unknown clinical findings but the frequency of phenotype for wild allele A = 92 % and the phenotype frequency for mutant allele G = 50 %.

At the same time for 50 control subjects were investigated for the Cytotoxic T Lymphocyte Association-4 +49 A / G polymorphism respectively with patients on same Single Nucleotide Polymorphism, as following : AG = 40 % ; AA = 54 % ; GG = 6 % ; A = 74 % ; G = 26 % ; A = 94 % and G = 46 %.

The distribution of Cytotoxic T Lymphocyte Association -4 + 49 A / G genotype frequency did not differ significantly between patients and controls (P = 0.885).

The result on the other Single Nucleotide Polymorphism -318 C / T Showing the frequency of genotype ; for heterozygous (CT = 16 %), homozygous wild allele (CC = 84 %), homozygous genotype for T allele = 0 %.

Normal allele C = 92 %, but for mutant allele is (T = 8 %) with unknown clinical finding, where the phenotype for wild allele is (C = 100 %), phenotype mutant allele is T = 16 %.

On the other hand for control subject investigated for Cytotoxic T Lymphocyte Association -4 -318 C / T polymorphism were (CT = 22 %, CC = 74 %, TT = 4 %, C = 85 %, T = 15 %, C = 96 %, T = 26 %) respectively.

The result of distribution of Cytotoxic T Lymphocyte Association -4 -318 C / T genotype frequency did not differ significantly with type 1 diabetes mellitus patients and controls (P = 0.248).

Conclusion : this case-control study suggests that the +49 A / G Single Nucleotide Polymorphism of the Cytotoxic T Lymphocyte Association-4 gene is not strongly associated with type one diabetes mellitus in Jordanian population, the apparent discrepancies between the present study and other studies could be due to the genetic heterogeneity among the population studied.

The Cytotoxic T Lymphocyte Association-4 49 A / G Single Nucleotide Polymorphism may not be the true disease associated variant but a marker in linkage disequilibrium in different population.