Slc9a6, also known as the sodium/hydrogen exchanger 6 (NHE6), is an alkali cation/proton exchanger that regulates recycling endosomal pH homeostasis and trafficking. It is involved in important biological processes within cells, and its function is crucial for normal cellular activities [2,3].

In the shaker rat, a naturally occurring mutation in Slc9a6 leads to progressive ataxia characterized by Purkinje cell loss. An adeno-associated virus (AAV) targeting Slc9a6 expression to Purkinje cells using the mouse L7-6 (L7) promoter reduced the shaker motor, molecular and cellular phenotypes, suggesting AAV-based gene therapy may be a viable therapeutic strategy for Christianson syndrome, which is also caused by Slc9a6 mutation [1]. In a Nhe6 knockout (KO) mouse model of Christianson syndrome, the mice had decreased nocifensive responses to acute noxious thermal, mechanical, and chemical stimuli, indicating that NHE6 is a significant determinant of nociceptor function and pain behaviors impaired in this syndrome [3].

In conclusion, Slc9a6 plays essential roles in maintaining endosomal pH homeostasis and trafficking, which are crucial for normal cellular function. The gene knockout models, such as the shaker rat and Nhe6 KO mice, have revealed its significance in diseases like Christianson syndrome, highlighting its potential as a therapeutic target for related neurological disorders.