DHFR and spina bifida: A study on the mothers of individuals with spina bifida showed that the messenger ribonucleic acid (mRNA) expression of the DHFR gene was 50% higher in the del/del genotype than in the ins/ins genotype.11 Moreover, in a study on women with breast cancer, Xu et al.12 also observed mRNA concentrations that were 2.4 and 4.8 times higher in individuals with the ins/del and del/del genotypes, respectively, in comparison with individuals with the ins/ins genotype.