This suggestion was based on the facts that the PregS level-regulating steroid sulfatase (STS) enzyme deficiency is positively linked to mental health conditions and depression in human patients (Cavenagh et al., 2019) and PregS levels were reportedly increased in STS-deficient patients (Sánchez-Guijo et al., 2016). The gene discussed is STS; the disease is depressive symptom measurement.