Association of estrogen and progesterone receptor polymorphisms with idiopathic thin endometrium

The research question is as follows: Are estrogen and progesterone receptor genotypes associated with thin endometrium? We performed a prospective cohort study of 129 patients who underwent preimplantation genetic testing for aneuploidies. These patients were categorized according to endometrial thickness: >7 mm control group ( n  = 94) and ≤7 mm study group ( n  = 35). Polymorphisms in the genes ESR1 (rs9340799 and rs3138774), ESR2 (rs1256049 and rs4986938), and PGR (rs1042838) were analyzed. Regarding genotype distribution, the GA/AA genotype frequency for rs4986938- ESR2 was higher in the thin endometrium group (80% in the study group vs. 50% in the control group; P  = 0.002), as well as the GG genotype of PGR (8.6% in the study group vs. 0% in the control group; P  = 0.002). No differences were observed for the remaining genotypes. In terms of clinical data, the pregnancy rate after euploid embryo transfer was lower in patients with the AA genotype for rs4986938- ESR2 (18.2% AA vs. 40.8% GA vs. 44.0% GG; P  = 0.039). Finally, a predictive pregnancy model was developed using clinical data and ESR2 and PGR genotypes, with an area under the curve of 0.76, sensitivity of 64%, and specificity of 76%. The genetic variants rs4986938 in the ESR2 gene and rs1042838 in the PGR gene seem to correlate with idiopathic thin endometrium. In addition, the rs4986938 polymorphism in the ESR2 gene is associated with pregnancy rate. Finally, a predictive model combining clinical data and patient genetic profiles has been proposed to predict clinical pregnancy outcomes.