Pcdh15^av is a waltzing type mutation that arose in the K strain and is inherited independently of the Cdh23^v waltzer mutation (J:14990). Viability and fertility are about normal, but females are poor mothers. Homozygotes show the typical circling, head-tossing, deafness, and hyperactivity of the circling mutants. Later, hair cells and spiral ganglion cells degenerate. The permeability of the stria vascularis appears to be normal (J:5225). This mutation is probably extinct (J:106625).