Objective: To explore the frequencies and polymorphic distribution of intron 4 of programmed cell death 1 (PDCD1) gene, and to analyze its relation to the susceptibility of developing systemic lupus erythematosus (SLE) in indigenous Han Chinese from Anhui province.
Methods: Blood samples from 122 patients with confirmed SLE and 143 controls were collected for a case-control study. DNA of the subjects was extracted and amplified by polymerase chain reaction (PCR). The single nucleotide polymorphisms(SNPs) of PDCD1 7809 locus,7872 locus and 8162 locus were further confirmed by direct DNA sequencing and BLAST.
Results: The PDCD1 7809 locus was indentified as type G/G among all the subjects investigated. There were significant difference at PDCD1 7872 locus with C/T polymorphism and 8162 locus with G/A polymorphism between SLE patients and controls (Chi2 = 8.55, chi2 = 11.85, P<0.05). The frequencies of genotype for 7872 locus with types of C/C, C/T and T/T in SLE patients were 36.1% 41.8% and 22.1%, while in control they were 51.7%, 35.0% and 13.3%, respectively. There was significant difference in the frequency of mutation in 7872 locus between SLE patients and controls (chi2 = 7.411, P<0.05). The genotype frequencies of PDCD1 8162 locus G/G, G/A and A/A in SLE patients were 50.1%, 20.3% and 28.6%, while in control they were 57.6%, 20.8% and 22.6%, respectively. There was significant difference in the frequency of mutation in 8162 locus alleles between SLE patients and controls (chi2 =7.547, P<0.05). The genetypeof PDCD1-7809(C/T) and PDCD1-8162(G/A) seemed to have the function of preventing the development of SLE ( OR = 0.583, OR = 0.485).
Conclusion: The genotype of PDCD1 gene 7809 locus was G/G in all indigenous Han Chinese, while the SNPs of PDCD1 gene 7872 locus and 8162 locus might affect the susceptibility to SLE development.