The sarcomere structure of the body wall musculature appears normal in third instar homozygous larvae.

Only around 20% of homozygous TBPH^DD96 mutant flies eclose as adults. The majority of flies die during late larval/pupal stages. The surviving flies have shortened lifespan, dying at around day seven in comparison with wild type controls that have a lifespan of ~80 days. Third instar larvae exhibit impaired peristalsis and defective locomotion and adults have non-existent or severely impaired innate escape and climbing behaviours. TBPH^DD96 mutant flies show a reduction in walking activity over time, activity and total distance travelled compared with controls. Walking velocity is also reduced compared to controls. Severe gait abnormalities are seen.

No defects are seen in TBPH^DD96 mutant NMJ synapse structure and morphology compared to age-matched controls.

TBPH^DD96 mutant flies show decreases in both the amplitude and frequency of the miniature excitatory junction potentials (MEJPs). Low-frequency stimulation showed no difference in evoked excitatory junction potential, resulting in an increased quantal content. No differences are seen following high-frequency stimulation.

The electroretinograms from TBPH^DD96 mutant 1 and 5 day old flies in response to blue light pulses are similar in peak-peak amplitude to controls. However these flies have 15% reduction in the off-transient.