PITX1 and hydrops fetalis: Indeed, Xenium analysis of hair follicles in PITX1+ skin corroborated this loss of HF Stem Cells while the proportion of terminally differentiating Anagen HF keratinocytes (evidenced by the expression of markers of terminal differentiation such as Dlx3 and Dsg4) massively increased, leading to HF hypertrophy (Supplemental Figure 4, E and F).