CLDN1 and Fabry disease: While UPodo were defined based on positive staining for podocalyxin (PCX) and negative staining for claudin-1 (CL1), the morphology of Upodo was not uniform (Fig 1A–1P); 35 ± 17% of UPodo in patients with Fabry disease and 30 ± 14% of these in healthy subjects (p = 0.21) had small shrunken/fragmented nuclei with apoptotic appearance (Fig 1I–1L), while the rest had normal appearing nuclei.