Genetic linkage and radiation hybrid mapping of the three human GABAC receptor ρ subunit genes: GABRR1, GABRR2 and GABRR3

GABAC receptors mediate rapid inhibitory neurotransmission in retina. We have mapped, in detail, the human genes which encode the three polypeptides that comprise this receptor: ρ1 (GABRR1), ρ2 (GABRR2) and ρ3 (GABRR3). We show that GABRR1 and GABRR2 are located close together, in a region of chromosome 6q that contains loci for inherited disorders of the eye, but that GABRR3 maps to chromosome 3q11-q13.3. Our mapping data suggest that the ρ polypeptide genes, which are thought to share a common ancestor with GABAA receptor subunit genes, diverged at an early stage in the evolution of this gene family