Asic5, also known as bile acid-sensitive ion channel (BASIC), is an orphan member of the acid-sensing ion channel (ASIC) family in the Degenerin/Epithelial Na+ channel (Deg/ENaC) family. ASICs are ligand-gated ion channels activated by extracellular protons and play roles in various physiological and pathological processes in the nervous system [3,4,5,6].

In the Asic5 knockout mouse model, deletion of Asic5 impaired motor performance. It decreased the intrinsic excitability of type II unipolar brush cells (UBCs) in the vestibulocerebellum, reducing spontaneous action potential firing. Although there was some compensation through suppression of certain K+ currents, the overall loss of Asic5 led to altered temporal processing of vestibular input, contributing to cerebellar ataxia [1]. Additionally, whole-genome sequencing in humans identified a novel homozygous exonic variation in the ASIC5 gene in families with recurrent pregnancy loss. The mutation was found to be highly pathogenic, decreasing protein stability and preventing amiloride binding [2].

In conclusion, Asic5 is important for the activity of type II UBCs in the vestibulocerebellum, affecting motor coordination. Its dysfunction may also be associated with recurrent pregnancy loss. The gene knockout mouse models and human genetic studies have revealed these crucial roles of Asic5 in specific biological processes and disease conditions, providing valuable insights into the underlying mechanisms.