This mutation was found in the progeny of a neutron-irradiated male. Most homozygotes die soon after birth with cleft palate, but a few, presumably with unaffected or slightly affected palates, survive to maturity and are fertile. Female fertility is reduced; males have not been tested (J:2108). The p^cp mutation has been shown to be a deletion, which disrupts genes for three gamma-aminobutyric acid type A receptors, Gabra5, Gabrb3, and Gabrg3, which are clustered on Chr 7. The human homologs of these receptor genes are closely linked with the genes for Angelman and Prader-Willi syndromes (J:13583).