CLDN3 and helix rolling: In the absence of CLDN10b from these segments, e.g., in CLDN10b knockout mice and in TAL from a HELIX syndrome patient, CLDN3 (together with two further claudins, CLDN-16 and -19) is present in all TJ segments, i.e., also in those that are normally occupied by CLDN10b [19,24,38].