Our hypothesis is that BRAF/MEK inhibitors lead to hyponatremia and water retention (so-called dilution hyponatremia) by activating aquaporin 2 (AQP2) trafficking from its intracellular compartment to the luminal cell membrane, and by activating ENaC channel.
Dysregulation of AQP2 is also a common cause of water retention and hyponatremia that exacerbate the prognosis of congestive heart failure and hepatic cirrhosis.
The aim of our study was to investigate the distribution of single nucleotide polymorphisms (SNPs) of AQP1: rs1049305 (C/G) and AQP2: rs3741559 (A/G) and rs467323 (C/T) in 100 cirrhotic patients with ascites and to analyze their relationship with dilutional hyponatremia.
Water loading was followed by a very slow and incomplete elimination in the asymptomatic hemizygous boy with no suppression of AQP2 excretion and a delayed elimination in the heterozygous women because of an incomplete suppression of AQP2, and it induced hyponatremia in all NSIAD patients.