Deficiency of the β3 subunit of the type A γ–aminobutyric acid receptor causes cleft palate in mice

In addition to its function in the nervous system, γ-aminobutyric acid (GABA) has been implicated in mouse craniofacial development by the results of both teratological^1–3, and genetic studies⁴. We previously reported that disruption of the cleft palate 1 (cp1) locus, closely linked to the pink-eyed dilution (p) locus on mouse chromosome 7, causes a 95% penetrant, recessive, neonatally-lethal cleft palate (CP) in mice homozygous for the p^4THO-II deletion⁴. We proposed that the β3 subunit gene (Gabrb3) of the GABA_A receptor might be a candidate for cp1 (ref. 4); our earlier studies^4,5 had localized cp1 to an interval beginning distal to the gene for the GABA_A receptor α5 subunit (Gabra5) and ending within the Gabrb3 coding region. To test the hypothesis that deletion of Gabrb3, and not another gene in the interval, causes CP, we performed an experiment to rescue the CP phenotype by introducing a Gabrb3 trans-gene into p^4THO-II homozygotes. We now show that such transgenic mice are phenotypically normal, indicating that Gabrb3 is indeed the cp1 locus.