In a Brazilian case-control study examining plasma HO-1 levels and (GT)n repeats in preeclampsia (n = 91) and healthy patients (n = 90) in 2019, there was no significant difference in plasma HO-1 levels and the LL or LS + SS allele frequency of (GT)n repeats between the two groups [48]. This evidence concerns the gene HMOX1 and preeclampsia.