In nompA¹/nompA² flies the sensory neurons associated with each bristle often fail to reach the bristle. The detached processes may be bent, curled or club shaped. Campaniform sensilla of wing vein L3 show a similar short fall in sensory neuron. In embryos the PNS appears normal. nompA¹/nompA² flies are uncoordinated with characteristic leg crossing and upheld wings. The phenotype is effectively lethal. nompA¹/nompA² flies show no change in TEP (transepithelial potential) in response to stimulation of thoracic bristle. Sound evoked potentials are absent from antennal chordotonal organs. The scolopidial array is disorganized and separated from its apical attachment site. The scolopales and sensory ciliary structures appear normal, but showed defects in the dendritic caps and their attachment to the cilia.

Flies are uncoordinated showing frequent leg crossing and wings held up or out. Walking and righting ability is impaired. Spontaneous or induced (by light or mechanical stimuli) activity is vigorous. Mechanoreceptor potentials are invariably absent in thoracic macrochaete bristles. The sound evoked response (measured via the antennal nerve) is eliminated. ERGs are normal.