PIEZO1 and anemia (phenotype): Gain-of-function mutations also occur: The disease phenotype is again restricted; in this case to anemia, consistent with an important role of Piezo1 in erythrocyte hydration.48–51 More genetic associations are emerging: an outstanding variant identified in varicose vein genome-wide association studies was PIEZO1. 46 The mechanistic explanation is not yet clear but the observation supports the hypothesis of vascular significance of Piezo1.