Analysis of HLA-G Polymorphisms in Couples with Implantation Failure



Maria da Graça Bicalho, Laboratório de Imunogenética e Histocompatibilidade, Departamento de Genética, Universidade Federal do Paraná, R. Cel. Francisco H. dos Santos S/N, Centro Politécnico – Jardim das Américas, CP 19071, CEP 81.530.990, Curitiba, PR, Brazil. E-mail:



HLA-G expression is related as an immune modulator of fetal–maternal tolerance, and its levels was correlated with pregnancy outcome. In a case–control study, we investigate the association between the genetic variability of the HLA-G gene and serum levels of soluble HLA-G in cases of embryo implantation failure.

Method of Study

Forty couples with at least two unsuccessful fresh embryo transfers (implantation failure; IF) and 83 fertile couples with at least two successful pregnancies was genotyped by sequencing-based typing. HLA-G alleles were defined by nucleotide sequence variations at exon 2, 3, and 4, and the quantification of soluble HLA-G (sHLA-G) was performed by ELISA.


There was a significant difference between the HLA-G allelic distributions between IF couples and the control couples. The HLA-G*01:03:01 allele was increased in the IF couples. There were no significant differences in the serum levels of sHLA-G in the IF and control groups.


The results suggest that the distribution of HLA-G products may play a significant role in the modulation of maternal–fetal immune response.