Ala16Val SOD2 polymorphism is associated with higher pregnancy rates in in vitro fertilization cycles

ObjectiveTo investigate whether the Ala16Val polymorphism in the SOD2 gene, encoding for mitochondrial manganese superoxide dismutase (SOD), is associated with [1] infertility and [2] the pregnancy rate (PR) in IVF cycles.DesignProspective case-control study.SettingPublic university and public university hospital.Patient(s)A total of 362 newborns (nonselected population) and 148 infertile women undergoing an IVF cycle, from which 44 became pregnant and 104 did not.Intervention(s)Blood samples extracted from the patients and newborn umbilical cord.Main Outcome Measure(s)Genotype and allele distribution of the Ala16Val polymorphism in the SOD2 gene using the tetra-primer amplification refractory mutation system–polymerase chain reaction (PCR).Result(s)The polymorphism distribution of the subfertile women was similar to that of a nonselected population. The SOD2 Ala allele frequency was 49% both in controls and IVF patients. In IVF population the Ala/Ala SOD2 genotype was 25%, with a 28% Val/Val homozygous. In contrast, the Ala/Ala genotype was associated with higher PRs in IVF (47% in Ala/Ala vs. 23% in no Ala/Ala). A multivariate logistic regression analysis revealed that the Ala/Ala genotype was an independent predictor of pregnancy (odds ratio [OR] = 3.29), followed by the number of transferred embryos (OR = 2.37) and age (OR = 0.84).Conclusion(s)The Ala/Ala SOD2 genotype is a significant independent predictor of the occurrence of pregnancy in IVF. Data also support a role for antioxidant defense, particularly in the mitochondria, in conception in IVF.