Linkage disequilibrium and haplotype association analysis of the (CD28 rs3116496, CTLA4rs733618) genes in women of breast cancer in Baghdad

Abstract

Background: Breast cancer (BC) is one of the most common types of cancer among women worldwide. Chromosome 2q33 possesses several genes that encode immune-regulating proteins, such as co-stimulatory gene (CD28) and co-suppressive gene (T-lymphocyte-toxin protein 4 (CTLA4), two of the family of globulin genes that encode immunoglobulin proteins (sCD28, sCTLA4), and actes to the balance T-cell activation and thus act as an important natural barrier to the spread of breast cancer. Linkage disequilibrium (LD) which is means a nonrandom association of alleles at two or more loci on the same chromosome by chance within a one population. Method & Material: Collected the sample of study which included (93) samples from women with breast cancer, and (50) samples from healthy women, the ages of the infected and healthy women ranged between (30-70), and DNA was extracted for all samples, and the were confirmed the concentration and purity by spectrophotometry. Genotypes were detected by real-time PCR for each SNPs (CTLA4, rs733618 C>T) and (CD28, rs3116496 C>T), and then calculated the linkage Disequilibrium (LD) by a number of mathematical equations in addition to using the Hardy Weinberg calculator on the Internet. Result: The results of real-time PCR reactions for a gene polymorphism (CD28, rs3116496 C>T) for a sample of women with breast cancer had genotypes (TT, TC, CC) and (48, 24, 21), respectively. While the polymorphism was (CTLA4, rs733618 C>T) for the female patient sample is (TT= 21, TC= 17, CC= 55), and the calculated D represents the linkage Disequilibrium, the value is (0). Discussion: In this Study, D = 0, and r² = 0, which indicates that the community correlation equilibrium and there is no LD between polymorphism of the two genes (CD28) and (CTLA4) in women with breast cancer, and this indicates polymorphism of the two genes located in the region of chromosome 2q33 are not associated with an increased risk of breast cancer in Baghdad city.