Wnt4C1/Wnt4EMS23 mutant exhibit occasional misrouting of ventral axons towards the dorsal lamina. In extreme cases, ventral axons appear as if they are about to project to ventral lamina but then veer towards the dorsal lamina. Ventral misrouting is seen in the larval optic stalk.
Lethality acts in first or second larval instar. 10%-15% of mutants survive to adulthood. Survivors are sterile, though show no external defects. Phenotype of homozygotes is similar to that of hemizygotes.