Since the primary phenotype observed in both Pcdhgtcko/tcko and Pcdhgdel/del is neuronal cell death, we crossed both mutant lines to Bax knockout mice (Knudson et al., 1995) to compare phenotypes when neuronal apoptosis is genetically blocked. Consistent with previous observations (Weiner et al., 2005), Pcdhgdel/del;Bax−/− pups show improved neurological function as compared with Pcdhgdel/del mutants, yet they still lack voluntary movements, and despite considerable efforts we were unable to recover any Pcdhgdel/del;Bax−/− mutants beyond P0 (Table 1 and Movie S2). Surprisingly, however, while some Pcdhgtcko/tcko;Bax−/− mutants die at P0, many live substantially longer despite being weaker and smaller than wild type and heterozygous pups. By culling littermates we were able to recover a number of Pcdhgtcko/tcko;Bax−/− mutants at weaning age. Some of these animals survived up to 6 months, although their persistent ataxia indicates neurological impairment (Table 1 and Movie S2).
