GABRR1 encodes the rho1 subunit of GABA-A receptors, which are pentameric ligand-gated chloride channels that mediate inhibitory neurotransmission. When activated by GABA, rho-containing GABA-A receptors selectively allow chloride anion flow across the cell membrane. Rho1 subunits are primarily expressed in the retina, where they facilitate retinal neurotransmission, and also localize to cerebellar Purkinje neurons where they mediate both synaptic and extrasynaptic inhibition. Beyond the nervous system, GABRR1 is expressed on hematopoietic stem cells and megakaryocyte progenitors, where GABA signaling through the receptor promotes platelet generation 1. Genetically, GABRR1 variants associate with alcohol dependence in European American families, particularly those with earlier disease onset 2. At the molecular level, a single histidine residue (His156) in the extracellular domain is critical for modulation by zinc and other transition metal cations 3. The N-terminal region contains signals directing both homooligomeric assembly of rho1 subunits and heterooligomeric interaction with rho2 subunits 4. Clinical associations include altered DNA methylation in schizophrenia patients with tardive dyskinesia 5, and suggestive links to diabetic nephropathy in type 2 diabetes and refractive error in Asian populations with gene-environment interactions involving education level 6. These findings indicate GABRR1's broader role beyond canonical GABAergic inhibition.