Van gen naar ziekte; van vasopressine-V2-receptor en aquaporine 2 naar nefrogene diabetes insipidus

- In the kidney, binding of arginine vasopressin to the vasopressin type-2 receptor (V2R) causes redistribution of aquaporin-2 (AQP2) water channels from intracellular vesicles to the apical cell membrane, a process which initiates urine concentration. This is disturbed in nephrogenic diabetes insipidus due to mutations in the V2R gene, which lies on Xq28 and has a sex-linked recessive heredity, or the AQP2 gene, which lies on chromosome 12 and has an autosomal heredity. In the case of a recessive abnormality the AQP2 protein which does not fold properly, remains in the endoplasmatic reticulum and is then broken down by a protease. For a dominant abnormality the transport sig-nal in the AQP2 protein changes which results in it being found in another part of the cell namely the Golgi apparatus.