The most common screening method is nowadays the first trimester combined test which consists of a Bayesian analysis of the a priori risk of maternal age for Down’s syndrome, and the posterior risk combining serum biomarkers such as beta fraction of the human chorionic gonadotropin (β-hCG), pregnancy associated plasma protein A (PAPP-A), and nuchal translucency measurement (Nicolaides, 2003; Alldred et al., 2017). Here, PAPPA is linked to Down syndrome.