Eggs laid by KCNQ64B homozygous mothers fail to hatch into larvae. This embryonic lethality is only associated with homozygous KCNQ64B mothers. Homozygous KCNQ64B males have normal fertility, as they produce adult progeny when mated to wild-type females. Heterozygous embryos from homozygous KCNQ64B females and wild-type males still fail to hatch, even with a copy of the wild-type gene from the male. The lack of paternal rescue indicates that the time window when KCNQ is critical lies before the zygotic expression of the gene.
The nuclei of 1-2 hour old KCNQ64B mutant embryos are disorganised in comparison to wild-type. Some nuclei appear to be broken down into smaller fragments, whereas others have clustered abnormally, indicating that development of the mutant embryo is arrested before the cellularisation stage.