Wnt2^L/Wnt2^O transheterozygous mutant males exhibit missing or incompletely developed testes. This phenotype is variable, with approximately 10% of the transheterozygous males being fertile.

The brains of Wnt2^O/+ mutants show a reduction of dorsal cluster neuron crossing to the medulla (from the wild-type axon number of 11.7 to 7.3 in the mutants).

In homozygous mutant adults, the pattern of direct flight muscle (DFMS) is different from wild-type. Muscle 52 normally attaches to a peduncular dorsal apodeme, and a ventral swath of epidermis, forming a fan shape. In mutants muscle 52 often attaches to the correct dorsal apodeme, but attaches inappropriately to a ventral apodeme normally used only by muscles 49 and 50. Occasionally muscle 53 appears spit or duplicated with half of it also attaching to the 49/50 apodeme. A normal muscle 54 is seen in only 6% of adults.

Mutants are viable and have normal abdomens.

With variable penetrance, homozygous males have much smaller testes than wild-type. The hub cells, cyst cells and terminal epithelial cells are present. The germ cell lineage is also present. The outermost pigment layer, which normally covers both the testis and seminal vesicles, is absent. The muscle cell layer of the testis sheath is malformed or incomplete. Testis colour: the testis sheath lacks yellow pigmentation. Homozygotes have held out wings.