ELN and pseudoxanthoma elasticum (inherited or acquired): Abnormal elastic fibers are thought to be produced by the PXE skin fibroblasts (Quaglino et al., 2000), but could also occur with normal fibroblasts in the presence of PXE serum (Le Saux et al., 2006) or in presence of elastin degradation products (Simionescu et al., 2005).