While the role of TGF-β which modulates trophoblastic proliferation and differentiation in human fetal growth and preeclampsia, as shown in these studies, has not been extensively studied in humans, and indeed the results are conflicting on its precise role in pregnancy, some of the studies were limited either by the small sample size or lacked methodological clarity (e.g., failure to clearly define how the study population was identified). The gene discussed is TGFB1; the disease is preeclampsia.